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Volkswagen Corrado Repair Manual: 1990-1994

Volkswagen repair manual index:
ABCDEFGHI J K LM N O P Q RST U VW X Y Z

A

Grounded by the Digifant E.C.U., the fuel pump relay provides battery voltage to the fuel pump, injectors, idle stabilization control unit, oxygen sensor heating element and the power steering pressure switch. When energized by the ignition switch, the power supply relay provides battery voltage to the Digifant ECU. Coolant Temperature Sensor. Digifant ProTraining Manual Double-sided Digifant ProTraining Manual Single-sided Take a look/read and if you find any errors, or think anything should be added, let me know. Once the revision is finalized, I'll see if Everett wouldn't mind hosting it here on TheSamba for permanent, easy downloading.

ABS
see Anti-Lock Brake System or On Board Diagnostic (ABS)
Air filter
see Owner Information
Alignment
see Wheels, Tires. Wheel Alignment
Alternator
see Electrical-Battery, Starter, Generator
Anti-freeze
see Engine-Cooling System
Air Conditioner
Systems using R-134a refrigerant see Supplement
Systems using R12 refrigerant
-A/C compressor assembly 87.22 clutch
checking 87.9
removing/installing 87.23 lines
installing 87.9a shaft seal
removing/installing 87.28 valve plate, head and gasket
removing/installing 87.35
-A/C pressure switch checking 87.7
-A/C system fuses 87.7 relays
location 87.8
temperatures and pressures
checking 87.16
-Air distribution and evaporator case assembly 87.10
-Belt and pulleys assembly 87.21
-Belt tensioning damper assembly 87.20
-Engine components mounting 87.18
-Evaporator water drain valve
identifying/removing 87.9
expansion valve insulator
checking 87.9
-Refrigerant system
components 87.5
discharging 87.3
oil specifications 87.4a
safety measures 87.2
-Safety relief plug
identifying 87.8
-Sight glass
checking 87.8
-Troubleshooting
air conditioner
does not cool 87.46
compressor clutch does not engage 87.48
cooling output diminishes after several minutes 87.51
Insufficient cooling output 87.50
defroster
does not clear windshield 87.44
fresh air
cannot be shut off 87.39
no air flow from dash board or foot well vents 87.42
heater insufficient or no heat output 87.40
-Vacuum system
checking 87.13
hose layout 87.12
reservoir removing/installing 87.15
servos checking 87.14
Anti-Lock Brake System (ABS)
-Hydraulic modulator assembly
with EDL 45.7
without EDL 45.3 removing/installing 45.6
-Pressure warning switch removing/installing 45.5
-Repair work general notes 45.2 repair rules 45.2
ATF (automatic transmission fluid) see Automatic Transmission-Controls, Housing
Automatic Transmission-Case,
Gears, Shaft
1st to 3rd gear clutch (K1) with turbine shaft assembly 38-130
-2nd/4th gear brake (B2) adjusting 38-90
-3rd/4th gear clutch (K3) With pump shaft assembly 38-170
circlip for clutch spring support
replacing 38-160
ATF pump assembly 38-100
-Clutches K1 /K2 adjusting/checking freeplay 38-80
disassembling/assembling 38-140
-One-way clutch with B1 piston assembly 38-110
disassembling/assembling 38-120
-Parking lock assembly 38-210
installing 38-220
-Planet carrier adjusting/checking 38-60
-Reverse brake (B1) adjusting/checking 38-70
--Reverse clutch (K2)
assembly 38-150
circlip for clutch spring support
replacing 38-180
-Transmission assembling 38-50
assembly 38-30 clutches/brakes
installed positions 38-10
disassembling 38-40
selector/clutch/brake engagement chart 38-20
-Valve body
assembly 38-190
disassembling/assembling 38-200
Automatic Transmission-Controls, Housing
096 automatic transmission -ATF cooler/ATF filler tube
assembly 37-70 -ATF filter
replacing 37-80 -Automatic shiftlock
troubleshooting 37-110
-Identification 00.3a. 00.3b
-Removing/installing 37-60
-Shift points
checking 37-90 -Stall speed
checking 37-100 -Selector lever/detent
segment/solenoid switch
adjusting 37-40 assembly 37-30
-Selector mechanism assembly 37-20 support
removing/installing 37-50
-Technical data
chart 37-10

B

Battery
see Electrical-Battery. Starter. Generator or Owner Information
Belts
see Electrical-Battery Starter. Generator
Body
-Acid rain repairing 50.11
-Body dimensions door opening 50.4
floor section 50.2
front section 50.4
rear section 50.5
-Front fender adjusting 50.7 mounting 50.6
-Head lamp removing 50.9
-Lock support
assembly 50.8 removing/installing 50.10
-Shroud removing/installing 50.9
Body Accessories-Exterior
-Mirror glass removing/installing 66.8
-Radiator grille removing/installing 66.5
-Rear spoiler installing 66.5 removing 66.4
-Rearview mirror assembly 66.7 removing/installing 66.8
-Rocker panel protective molding
replacing 66.9
-Roof trim molding removing /installing 66.3
-Wheel house liner assembly 66.6 installing
1991 m.y. 66.6a
Body Accessories-Interior
-Automatic shoulder belt system (USA only) assembly 68.2
door frame track trim
removing/installing 68.4 drive unit
installing 68.4 removing 68.3 knee bar
removing/installing 68.4 knee bar support bracket
removing/installing 68.5 seat switch release magnet
removing/installing 68.6 shoulder belt release magnet

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installing 68.6
removing 68.5
-Automatic shoulder belt troubleshooting (USA only)
belts do not move to A-pillar
after removing ignition key
(driver or passenger side) 68.17 belts only move to A-pillar
door opened with key removed
(driver or passenger) 68.16
both belts do not move to B-pillar
doors shut, ignition ON 68.9 belt does NOT move to A-pillar
when door opened 68.13
belt does NOT move to B-pillar 68.11
driver belt moves to A-pillar
when vehicle shifted into reverse 68.18
seat belt warning light comes on
with belts connected and ignition on 68.20
seat belt warning light does not light
belts at B-pillar, ignition ON 68.19
wiring diagrams 68.21
-Child seat
installing on front passenger seat 68.31
-Interior mirror
removing /installing 68.8
-Rear seat belt assembly 68.7
buckle removing/installing 68.8
mounting removing /installing 68.8
-Seat belts inspecting 68.24
Body-Front Doors
-Central locking assembly 57.9
bi-pressure pump
removing 57.10
checking 57.13
electrical troubleshooting 57.14
gas flap activator,
adjusting 57.11a
removing/installing 57.11
master activators
removing/installing 57.10
pump/control module
location 57.17 rear lid activator
removing/installing 57.12
-Door lock checking 57.6
door lock
removing/installing 57.8
inner handle
removing 57.7 installing 57.7 locks
re-keying 57.18
-Front door assembly 57.2
impact bar
removing 57.5 removing/adjusting 57.3
seal
removing/installing 57.8
-Window regulator bordering frame
removing/installing 57.4
carrier to glass
bonding 57.3
drilling out rivet 57.3
removing/installing 57.3
Body-Seats
-Center armrest removing/installing 72.3
-Front seat backrest
removing/installing 72.2
removing/installing 72.2
-Rear seat backrest
removing/installing 72.4
removing/installing 72.3
Brake fluid
see Brake-Hydraulic Components
Brake-Hydraulic Components,
Regulator, Booster
-Brake booster/master cylinder assembly 47.13
-Brake caliper piston
pre-bleeding 47.7 removing/installing 47.3, 47.6, 47.7
seal
removing/installing 47.3, 47.6
-Brake fluid replacing
with ABS 47.11
without ABS 47.15
-Brake pressure regulator checking/adjusting 47.8
-Brake system bleeding
with ABS 47.9
without ABS 47.14
-Front brake caliper component layout 47.2
-Rear brake caliper component layout 47.5
Brake-Mechanical Components
-Brake caliper removing 46.4
-Front brake assembly 46.3
pads
removing/installing 46.4
-Brake pedal assembly 46.9
-Parking brake adjusting 46.8 assembly 46.7
-Rear brake assembly 46.5 pads
replacing 46.6
-Technical data chart 46.2
Bumpers
-Front bumper assembly 63.2
gap dimension 63.4 removing/installing 63. 3
-Rear bumper assembly 63.5
gap dimension 63.6 removing/installing 63.6

C

Central locking
see Body-Front Doors
Clutch
02A 5-speed manual transmission
-Clutch
assembly 30.7 removing/installing 30.8
-Clutch diaphragm spring ends checking 30.8
-Clutch pedal assembly 30.2
-Clutch release assembly 30.5
Dolt torque 30.7 --Hydraulic components
assembly 30.4 -Main shaft seal
driving in 30.6
replacing 30.9 --Pressure plate
replacing 30.9 -Return spring
removing/installing 30.3 -troubleshooting
chart 30.10
Compression pressure
See Engine-Cylinder Head Valve Drive
Constant velocity (CV) joints
see Front Wheel Suspension-Shafts and Axle
Coolant fan
See Engine-Cooling System
Cruise control
see Electrical-Battery, Starter, Generator or Electrical System-Lights
Cylinder block
See Engine-Crankshaft/Crankcase
Cylinder head
See Engine-Crankshaft/Crankcase

D

Differential--Automatic Transmission
-Axle flange oil seal removing/installing 39-10
---Differential adjusting 39-130
assembly 39-80
disassembling 39-90
modification 39-85
-Differential pinion assembly 39-60
removing/installing 39-70
-Final drive/differential assembly 39-60
removing//installing 39-70
--Output gear
adjusting 39-120
assembly 39-20
removing/installing 39-3C
-Pinion
adjusting 39-110
assembly 39-40
removing/installing 39-50
--Shims/bearings
installed positions 39-100
Differential-Manual Transmission 02A 5-speed
-Bearings inner race
removing/installing 39.5 outer race
removing/installing 39.5
-Differential adjusting 39.8 assembly 39.4 gears
installing 39.7
-Drive flange oil seal installing 39.5
replacing 39.2
-Final drive gear installing 39. 7
removing 39.6
-Gear
installing 39.7
-Rivet heads boring 39.6
--Roll pins installing 39.7
-Turning torque checking 39.10

E

Electrical-Battery, Starter, Generator
-Battery
charging 27.4
checking 27.3
jump starting 27.5
load testing 27.6
removing/installing 27.2
troubleshooting 27.7
voltage test 27.6
-Belt routing
vehicles with AC 27.13
vehicles without AC 27.12 tensioning 27.12
-Cruise control system checking/adjusting 27.15 component layout 27.14 vacuum system
leak testing 27.17
-Generator components layout 27.10 removing/installing 27.11
-Generator (GEN) V-belt pulley removing/installing 27.12
-Starter motor removing/installing 27.8
Electrical System-Instruments 1990 M.Y.
-Digital clocK connector wiring 90.7
-Engine Coolant Temperature (ECT) gauge checking 90.14
connector wiring 90.6 troubleshooting 90.15
-Fuel gauge checking 90.13 connector wiring 90.6 troubleshooting 90.13
--Instrument cluster assembly 90.2 multi-point connector
identification 90.4 printed circuit
removing 90.8 removing 90.3 testing 90.10
-instruments removing/installing 90.5
--Light emitting diode (LED) installing 90.16
-Printed circuit removing 90.8
-Tachometer/oil pressure warning control unit
connector wiring 90.7
-Voltage stabilizer checking 90.9 removing/installing 90.7
-Warning light (left and right) installation position 90.6 From 1991 m.y
-Engine Coolant Temperature (ECT) checking 90.14
connector wiring 90.6 troubleshooting 90.15
-Fuel gauge checking 90.13 connector wiring 90.6 troubleshooting 90.13
-Instrument cluster assembly 90.17 multi-point connector identification 90.20 removing 90.19 lights
identification 90.24 removing/installing 90.24 testing 90.28
-Instruments removing/installing 90.21
-Light emitting diode(LED) installing (90.23
-MFA vacuum sensor removing/installing 90.27
-Printed circuit
component identification 90.26
-Turn signal indicator lights installing 90.23
-Vehicle Speed Sensor (VSS), speedometer (G22)
removing/installing 90.27
-Voltage stabilizer
checking 90.25
-Warning lights (left and right) installation position 90.22 removing/installing 90.23

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Anti-theft alarm system 1991-1992 m.y
-General information 90.31 -Troubleshooting
Alarm horn sounds but lights don't flash with alarm activated 90.40
Alarm system cannot be switched off 90.38 Alarm system cannot be switched on 90.33 Engine does not crank with alarm system off 90.41
From 1993 m,y
--General information 90.31
-Troubleshooting
activated alarm system does not trigger alarm horn 90.50
activated alarm system does not trigger flasher lights 90 50
alarm cannot be switched off 90.49
alarm cannot be switched on 90.46
starter does not crank with alarm system switched off 90.52
Electrical System-Lights
-Additional brake light removing 94.18
-Back up light housing removing/installing 94.18
-Cruise control system connector wiring 94.11
-Fog lights adjusting 94.16
removing 94.16
-Front turn signal light removing/installing 94.16
-Headlights
adjusting 94.15
aiming 94.14
assembly 94.13
removing/installing 94.15
-Horn contact ring lubricating 94.3, 94.7
-Horn pad
removing 94.3, 94.7
-Horn plate removing 94.3, 94.7
-License plate lights removing 94.19
-Lock cylinder removing/installing 94.9
-Multi-function indicator connector wiring 94.11
-Side marker lights
removing 94.15
-Steering column assembly 94.2, 94.5
-Steering column switches connector wiring 94.10
wire routing (USA only) 94.12
-Taillight assembly 94.17
-Turn signal switch removing/installing 94.4 94.8
-Windshield wiper switch removing/installing 94.4. 94.8
Electrical System-Radio, MFA Radio
-Heidelberg VI fixed coded radio
coding a new or remanufactured radio 91.2
reactivating radio after reconnecting power 91.4
unlocking an electronically locked radio 91.5
Multi-function Indicator (MFA)
--Hall Vehicle Speed Sensor (VSS) checking (up to Aug. 1990) 91.24 contact plate removing/installing 91.7
location 91.6
-Multi-function indicator (MFA) cancelling the memories
(from 1993 m.y.) 91.53 connector wiring 91.6
driving data memory
(from 1993 m.y.) 91.52
general notes 91.6
instrument cluster
checking (from 1993 m.y.) 91.55
MFA check mode test
(from 1993 m.y.) 91.54
Multi-function Indicator Mode Select Switch (E 86) and Memory Switch (E 109)
(from 1993 m.y.) 91.53
operation and function (from 1993 m.y.) 91.52
printed circuit
identifying 91.8
removing 91.8
setting the time
(from 1993 m.y.) 91.53
vacuum sensor
removing 91.7
wiring (up to Aug. 1990) 91.25
(from Aug. 1990) 91.47
-Multi-function Indicator (MFA) self test (up to Aug. '1,9901,
checking 91.9
check mode test 91.9 measuring mode test 91.11
-Multi-function Indicator (MFA) self test (Aug. 1990 through 1992 m.y.)
checking 91.31
check mode test 91.31 measuring mode test 91.33
-Multi-function Indicator (MFA) troubleshooting (up to Aug. 1990)
ambient (outside) temperature display inaccurate 91.19 average driving speed indicator
is not accurate or displays '---'
or '0' 91.14
average fuel consumption display not accurate 91.15
clock inaccurate 91.13
clock operates in incorrect mode 91.13
display errors or no display 91_13
driving distance display not accurate 91.'4
driving distance display remains at 0 91 14
driving time remains at 0:00 91.14
-Multi-function Indicator (MFA)
troubleshooting (up to Aug. 1990) (cont'd)
memory cannot be
canceled/memory does not store information 91.21
no engine RPM display or engine RPM display faulty,
(while performing measuring
mode test) 91.17
oil temperature display inaccurate 91.20
'signal from speed sensor' display does not change (during measuring mode test) 91.24
-Multi-function Indicator (MFA) troubleshooting
(Aug. 1990 through 1992 m.y.) ambient (outside) temperature
display inaccurate 91.42
average driving speed indicator
is not accurate or displays '---'
or '0' 91.36
average fuel consumption display not accurate 91.37
clock inaccurate 91.35
clock operates in incorrect mode 91.35
display errors or no display 91.35
driving distance display not accurate 91.36
driving distance display remains at 0 91.36
driving time remains at 0:00 91.36 electronic speedometer and odometer
checking 91.44
memory cannot be canceled, memory does not store information. 91.39
oil temperature display inaccurate 91.43
tachometer inaccurate or does not work 91.45
Vehicle Speed Sensor (VSS), Speedometer (G 22)
checking 91.46
-Multi-Function Indicator (MFA) troubleshooting (from 1993 m.y.) average fuel consumption
display not accurate 91.57

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average speed display remains
at 0 or display not accurate 91.57 clock inaccurate 91.56
driving distance not accurate 91.57 driving distance remains at 0 91.56
driving time remains at 0:00 91.56
Multi-Function Indicator Mode Select Switch (E86), Memory Switch (E109) and wiring
checking 91.60
oil temperature display
checking 91.58
oil temperature display inaccurate 91.57
outside (ambient) temperature display
checking 91.59
outside (ambient) temperature display inaccurate 91.57
total or single trip memory of MFA not OK 91.56
Vehicle Speed Sensor (VSS , Speedometer
checking 91.63
Electrical System-Windshield Wiper & Washer
-Crank installing 92.3
-Rear window wiper assembly (1989) 92.7
(from 1990) 27.7a
-Rear wiper arm adjusting 92.8
-Rubber wiper inserts removing/installing 92.4
-Spray jets adjusting 92.6
--Windshield washer system 92.5
-Windshield washer pump
hose connections 92.6
-Windshield wiper assembly 92.2 troubleshooting 92.9
-Wiper arm
adjusting 92.3
angle, adjusting 92.8
Electrical System-Wiring
-Central locking system pump and control module
location/terminal identification 97.7
-Coolant fan control module location/terminal identification 97.8
-Connector terminal rubber grommet modifying 97.5
-Fuse/relay panel connections/plugs 97.3
identification 97.2
removing/installing 97.4
-Multi-point connector removing/installing 97.4
-Power window control module location/terminal identification 97.6
Engine-Assembly
-Engine code PG Engine/Transmission
adjusting 10.5
installing 10.3
mounting points 10.4
mounting points. hydraulic 10.4
removing 10.2
tightening torques 10.4
-Engine code-AAA
1! Engine/Transmission
installing 10.8
mounting points 10.10
I removing 10.6
tightening torques 10.11 - Identification
I type and model 00.2
engine /vehicle number location 00.2a -Technical data
charts 00.7
Engine-Cooling System Engine code-PG
-Coolant draining 19.5 filling 19.6 hydrometer
checking 19.6 mixture ratios 19.5
-Pump assembly 19.3 pulleys 19.4
-Radiator assembly 19.2
-Thermoswitch
checking 19.4
switching temperature 19.4 Engine code-AAA
-Coolant draining/filling 19.11 hydrometer
checking 19.6 mixture ratio 19.11
-Pump
assembly 19.9
auxiliary electric coolant pump
checking 19.19 fan control module
location 19.20 removing/installing 19.14
-Radiator/fan
assembly 19.7 removing/installing 19.13
-Thermostat assembly 19.17
Engine-Crankshaft/Crankcase Engine code-PG
-Clutch flywheel assembly 13.10
-Crankshaft, crankcase assembly 13.9 dimensions 13.12 ignition mark 13.12 oil seal
removing/installing 13.11
-Cylinder block assembly 13.4
-Cylinder head assembly 13.3
-Drive pelf installing 13.6
-G-charger. A/C brackets assembly 13.5
-Piston, connecting rod assembly 13.13
cylinder bore checking 13.15
dimensions 13.15 piston rings checking 13.14
pistons
checking 13.14
identification 13.14
Engine code-AAA
-Clutch, flywheel assembly 13.29
-Crankshaft
assembly 13.27 dimensions 13.31
oil seal, drive belt side removing/installing 13.26
-Cylinder block assembly 13.21 bore
checking 13.37
-Cylinder head assembly 13.19
-Drive chains
assembly sprockets 13.16
lower tensioner installing 13.24
marking direction of travel 13.18
-Pistons
assembly with connecting rod 13.32
checking 13.36
dimensions 13.38 rings
end gap, checking 13.34
side clearance 13.35
-Poly-ribbed belt removing/installing 13.25
-Valve timing adjusting 13.23
Engine-Cylinder Head, Valve Drive Engine Code-PG
-Camshaft assembly 15.5
identification 15.6 oil seal
removing/installing 15.9 play
checking 15.6
removing/installing 15.10
-Cylinder head assembly 15.2
compression
checking 15.4
distortion
checking 15.3
installing 15.3
-Valve
assembly 15.5
dimensions 15.6
exhaust valves
discarding 15.8a
guides
checking 15.11 replacing 15.11
hydraulic valve lifters checking 15,8
seats
refacing 15.7 stem seal removing/installing 15.12
Engine Code-AAA
-Camshaft
assembly 15.19
axial play checking 15.22
bearing caps installed position 15.21
removing/installing 15.27
-Compression pressure checking values 15.18
-Cylinder head assembly 15.13
distortion checking 15.16
gaskets replacing 15.15
installing 15.17
-Valves
assembly 15.14
dimensions 15.23 guides
checking -15.29
replacing 15.31 hydraulic valve lifters
checking 15.26 seats
replacing 15.24
stem seals removing/installing 15.32
Engine-Lubrication System
Engine Code-PG
-Dynamic oil pressure system
troubleshooting 17.6 -Lubrication system
assembly 17.2 -Oil
capacity, specifications 17.4
pan 17.3
pump
assembly 17.3
checking 17.4
gears 17.3 switches
checking 17.5 Engine Code-AAA
-Lubrication system assembly 17.11
-Oil
capacity, specifications 17.18
pump assembly 17.13
checking 17.15
relief valve checking 17.17
spray jet
removing/installing 17.16
warning system 17.18
Exhaust System-Emission Controls
Engine code-PG -Evaporative system leakage
troubleshooting 26.5
-Exhaust system
component layout 26.2
-Heated crankcase breather
checking 26.4
Engine code-AAA -EGR system
component layout 26.8
valve checking 26.9
-Exhaust system
component
removal/installation 26.7

F

Flywheel See Clutch
Fuel Supply Engine Code-PG
-Accelerator cable checking/adjusting 20.9
-Carbon canister component layout 20.16
shutoff valve
checking 20.17
-Fuel delivery rate checking 20.7
-Fuel pump
after run
checking 20.13 checking 20.10
check valve
checking 20.15 relay checking 20.12
removing/installing 20.11
-Fuel supply system component layout 20.2
-Rules of cleanliness chart 20.6
Engine Code-AAA
-Accelerator cable checking 20.22
adjusting 20.22
-Carbon canister component layout 20.32
-Fuel delivery rate
checking 20.27
-Fuel pump check valve
checking 20.29 checking 20.25 relay
checking 20.30
-Fuel supply/fuel pump assembly installation position 20.20
removing/installing 20.23
-Fuel supply system component layout 20.18
-Rules of cleanliness chart 20.6
-Vent valve checking 20.21
Front Wheel Suspension-Shafts &
Axle
Engine code-PG
-Axle shaft assembly 40.11
length 40.13
-Boot
installing 40.13
-Coil spring removing/installing 40.10
-Control arm bushing installing 40.4
pressing out/in 40.3
-CV Joint, inner assembling/checking 40.16
checking/disassembling 40.15
pressing off 40.12
pressing on 40.13
-CV joint, outer
assembling 40.15 checking/disassembling 40.14
removing 40.12
-Engine/transmission supporting 40.4
-Front suspension assembly 40.1, 40.6
-Steering knuckle/suspension strut separating 40.7
-Subframe mounting repairing 40.5
-Suspension strut assembly 40.9 strut nut
removing/installing 40.7
-Vibration damper removing/installing 40.12
-Wheel bearing pressing out/in 40.8
-Wheel hub pressing in 40.8 pressing out 40.7
Engine code-AAA
-Axle shaft
assembly 40.28 length 40.32
removing/installing 40.24
-Ball joint
checking 40.19a removing/installing 40.19b
-Coil spring removing/installing 40.27
-Control arm bushings removing/installing 40.19
-CV joint, inner
greasing 40.33 removing/installing 40.30
-CV joint, outer
greasing 40.33 removing/installing 40.30
-Front subframe assembly 40.17
-Front suspension assembly 40.20
-Suspension strut
assembly 40.26
nut
removing/installing 40.22 -Wheel bearing/hub
installing 40.23
removing 40.22
Fuel Injection, AFC System Engine Code-PG 49 States and Canada, 1989 m.y. to present California m.y. 1989-1990
-Basic throttle adjustment checking/adjusting 24-180
-Bypass valve adjustment checking 24-150
-Control unit
component layout 24-40
-Deceleration fuel shut-off checking 24-130
-Digifant system
under hood component layout 24-30
-Fuel injectors checking 24-170
-Fuel pressure regulator checking 24-160
-Full throttle enrichment checking 24-120
-Idle and full throttle switches
checking/adjusting 24-140
-idle speed and CO content
checking/adjusting 24-90
-Idle stabilization checking 24-100
-Intake air
component layout 24-20
--Oxygen sensor control
checking 24-110
general information 24-60
-Residual pressure checking 24-160
-Safety precautions
rules of cleanliness 24-80 safety measures 24-80
-Technical data
chart 24-70
-Throttle switches component layout 24-50
--Vacuum connections checking 24-190 Engine Code-PG California starting m.y. 1991
-Acceleration full throttle enrichment and deceleration fuel cut-off checking 24-240
-Basic throttle adjustment checking 24-320
-Bypass valve adjustment checking 24-310
-CO potentiometer checking 24-270
-Coolant temperature sensor checking 24-250
-Digifant System
under hood component layout 24-200
-Fuel injectors checking 24-300
-Fuel pressure checking 24 60
-Idle speed and CO content checking/adjusting 24-220
-Intake air temperature sensor checking 24-260
-Oxygen sensor and oxygen sensor control checking 24-230
-Residual pressure checking 24-160
-Throttle body
component layout 24-210
-Throttle potentiometer checking 24-290
-Vacuum connections checking 24-190
-Vacuum sensor checking 24-280 Engine Code-AAA
-Acceleration, full throttle enrichment and fuel deceleration shut-off checking 24-430
-Dashpot checking 24-420 adjusting 24-420
-Engine Coolant Temperature (ECT) sensor checking 24-440
-Fuel Injectors checking 24-470
-Fuel injection system component layout 24-370 repairing 24-340
-Fuel pressure regulator and residual pressure
checking 24-460
-Idle speed checking 24-400 control valve (ISC) checking 24-410
-Intake Air Temperature (IAT) sensor checking 24-480
-Motronic system component layout 24-330
engine control module component layout 24-350
intake air system component layout 24-360
throttle assembly component layout 24-380
-Safety precautions
chart 24-390
-Throttle position (TP) potentiometer
checking 24-450
Fuel tank
see Owner Information
Fuses
see Electrical System-Wiring

G

Glass, Window Regulators
-Power windows troubleshooting 64.20 control module
location 64.26
-Rear window assembly 64.11
installing 64.14
removing 64.12
-Side window assembly 64.16
installing 64.18
removing 64.17
-Window replacing general information 64.2
-Windshield assembly 64.5
installing 64.8
removing 64.6

H

Heater and Ventilation -Air intake duct
identifying 80.4
-Air outlet grill/housing
removing 80.4 -Control cables
installing/adjusting 80.5
-Fresh air blower
removing 80.5
series resistance
removing 80.5 -Heater
assembly 80.7
ventilation air ducts
assembly 80.2 -Heater/fresh air controls
faceplate/assembly
removing 80.4 -Side window air vent
removing 80.4
Hoods, Lids
-Gas-filled strut assembly 55.13
discarding 55.14
-Hood assembly 55.4
bowden cable
assembly 55.3
hinge
assembly 55.6
gap
adjusting 55.7
radiator support 55.3
rubber stop
adjusting 55.5
sound deadener
installing 55.5
striker
adjusting 55.5 support
replacing 55.14
-Rear lid adjusting 55.9
assembly 55.8
lid release
replacing 55.12 lock assembly 55.10 lock cylinder
replacing 55.11
lock repairing 55.11
rubber stop. adjusting 55.9 spring pin
removing 55.11
Hydraulic fluid
see Owner Information

I

Idle speed
see Fuel Injection AFC System
Ignition System
Engine Code-PG
49 States and Canada m.y. 1989 to present California m.y. 1989-1990
-Digifant ignition system component layout 28.2
-Hall sender unit checking 28.9 function
checking 28.10
-Ignition distributor installing 28.6
-Ignition timing checking/adjusting 28.7 map
checking 28.8 trigger function
checking 28.9
-Knock sensor checking 28.11
-Safety precautions chart 28.5
-Technical data, spark plugs 28.4 Engine Code-PG California starting m.y. 1991
-Digifant Ignition system component layout 28.12
-Control unit
component layout 28.13 technical data 28.15
-Hall sender checking 28.20
-Ignition coil, checking 28.19
-Ignition distributor, installing 28.16
-Ignition timing
advance, checking 28.18 checking/adjusting 28.17
-Safety precautions char, 28.14
Engine Code-AAA
production up to January, 1993
-Hall sender, checking 28.26
-ignition coil checking 28.25
-Ignition distributor
disassembling/assembling 28.22 -ignition aria spark plugs
technical data 28.23 -Motronic System
component layout 28.21 -Safety precautions
chart 28.24
Engine Code-AAA
production from January, 1993
see Supplement

L

Lifting vehicle
see Owner Information
Locks
see Body-Front Doors

M

Manual Transmission- Case,
Gears, Shafts
02A 5-speed
-1st gear
operating sleeve and hub
assembling 35.39
installing 35.40
shift forks, ball bearings changes 35.53 synchronizer ring checking 35.38
marking 35.39
-2nd gear
operating sleeve and hub assembling 35.39
installing 35.40 synchronizer ring checking 35.40
marking 35.40
-3rd gear
modifications 35.49, 35.50 needle bearing sleeve modified 35.50
operating sleeve/synchronizer hub disassembling/assembling 35.41
removing/installing 35.42 removing/installing 35.30 synchronizer ring checking 35.38
synchronizer sleeve modified 35.49
thrust washer modified 35.49
-4th gear
installing 35.29 modifications 35.49 needle bearing sleeve installing 35.42
operating sleeve/synchronizer nub disassembling/assembling 35.41
removing/installing 35.42 removing
with bearing and bushing 35.28
-4th gear (cont'd)
-shift forks
ball bearings
changes 35.53 synchronizer ring
checking 35.38 synchronizer sleeve
modified 35.49 thrust washer
modified 35.49
-5th gear assembly adjusting 35.16 adjusting, checking
(transmissions from 31 10 1) 35.55 gear
installing 35.15
removing 35.7
gear/synchronizer hub bolts modified 35.51 modified synchronizer installed position 35.55
modified synchronizer ring and 5th gear synchronizer
assembling 35.54 operating sleeve installing 35.16
removing 35.7
shift fork changes 35.54 installing 35.16 removing 35.7
synchronizer changes 35.53
synchronizer hub modified 35.51
installing with 5th gear 35.15
removing with 5th gear 35.7
synchronizer ring changes 35.53
checking 35.30
installing 35.15 synchronizer sleeve modified 35.52
-Backup light switch/socket pre-assembly 35.22
-Ball bearing inner race removing/installing 35.24
-Bearing sleeve removing/installing 35.21
-Differential assembly 35.5
installing 35.11
removing 35.10
--Drive flange shaft circlip
replacing 35.18 seal
replacing 35.17 shaft
installing 35.18
removing 35.6
-Gear carrier housing assembly 35.5 -Guide sleeve assembly
sealing ring
removing/installing 35.18
sleeve
installing 35.19
removing 35.6
-inner race
testing for wear 35.40
-Large pinion shaft bearing inner race
removing/installing 35.38
-Lock ring installing 35.24
-Main shaft adjusting 35.31 adjusting shim
chart 35.32
assembly 35.5 checking 35.34 disassembling/assembling 35.26 installing 35.11
removing 35.10
-Main shaft bearing inner race
installing 35.28 outer race
installing 35.28, 35.30
removing 35.28
-Needle bearing bushing
installing 35.29 installing 35.43, 35.47 removing 35.42, 35.47 revised
installing 35.52 sleeve
installing 35.41, 35.43
-Pinion shaft
adjusting 35.44 assembly 35.5 disassembling/assembling 35.35 installing 35.11
removing 35.10
-Reverse gear assembly disassembling/assembling 35.46 idler shaft
revised 35.52
manual Transmission- Case,
Gears, Shafts (cont'd)
-Reverse gear assembly (cont'd) idler shaft support
installing 35.11, 35.13
removing 35.8 modified 35.52 shift fork
installing 35.11
removing 35.9 sliding gear
installing 35.11
removing 35.9
-Sealing ring installing 35.21
-Selector shaft
changes 35.56 disassembling/assembling 35.20 end cover
changes 35.57 shaft assembly
installing 35.14
removing 35.8 support, bearing sleeve
removing/installing 35.14
-Shift fork assembly
assembly 35.5 installing 35.12 removing 35.9
disassembling/assembling 35.23
pivot pins
installing 35.13
removing 35.8
-Shift segments identification 35.24
installing 35.25
-Small pinion shaft bearing inner race
removing/installing 35.37 outer race
removing/installing 35.37
-Synchronizer ring
checking 35.38
sleeve w/hub and 1st gear
removing 35.39
-Transmission
adjustment overview 35.48
assembly 35.2
assembly stand
clamping in 35.6 disassembling/assembling 35.6
housing
installing 35.12
removing 35.8 housing cover
installing 35.17
modified 35.51
removing 35.6 identification 00.3 modifications 35.53
-Turning torque measuring 35.45
manual Transmission-Controls,
Assembly 02A 5-speed
-Gearshift cable/lever installing 34.6
-Gearshift housing repairing 34.7
-Gearshift lever repairing 34.8 rubber cover 34.9
-gearshift mechanism adjusting/checking 34.10
modifications vehicles w/ 6-cyl. engine 34.6a
repairing 34.4
-Selector housing cap installing 34.9
-Technical data chart 34.2
-Transmission controls
overview 34.3 removing/installing 34.12
multifunction Indicator (MFA) See Electrical System- Radio, MFA

O

Oil -Engine
see Engine-Lubrication System or Owner
Information
-Manual transmission
see Owner Information
Oil filter
see Engine-Lubrication System or Owner Information
Oil pump
see Engine-Lubrication System or Owner Information
On Board Diagnostic ABS
-Teves 02 ABS 01-1 on board diagnostic
ABS 01-3
ABS/EDL 01-53 electrical test
ABS 01-24
ABS/EDL 01-100
096 Automatic Transmission
-On Board Diagnostic 01-1
Fuel Injection and Ignition -Engine code PG-Digifant II 01-1
-Engine Code PG-Digifant 101-9
-Engine Code AAA 01-65
Owner Information
-Do-it-yourself service
changing a wheel 22 compact spare wheel 21 emergency starting 28
emergency towing with commercial towtruck 29
lifting vehicle
lifting points hoist/floor jack using hoist/floor jack 00.6 fuses 23
headlight adjustment 27
-Do-it-yourself service (cont'd) jack and tools 21 lifting vehicle 30 replacing bulbs 25 replacing the radio 28
-Gas station information servicing points 40
-Maintenance/lubrication schedule tables 41
-Technical description body/chassis 34 brakes 33 capacities/dimensions 37 emission control system 32 engine (4 cylinder) 31 engine (6 cylinder) 31 engine data/spark plugs (4 cylinder) 34 engine data/spark plugs (6 cylinder) 35 steering, suspension 33 transmission 33 v-belts (4 cylinder) 36 vehicle identification 38 weights 38
-Vehicle care
additional accessories, modifications and
parts replacement 20
air cleaner 11 battery 14 brake fluid 13
cleaning and protecting 2 cooling system 11 corrosion protection 5
difficult operating conditions 19 engine compartment 7 engine hood 7
engine oil filter 10
engine oil 8
fuel supply 1
fuel tank 1
maintenance 6
power steering 11
tires/wheels 16 transmission fluids 10 v-belt 13
windshield/rear window washer container 15 winter driving 20
Oxygen sensor (OXS)
see Fuel Injection-AFC System or Fuel Injection and Ignition-On Board Diagnostic (OBD)

R

Radio
See Electrical System-Radio, MFA
Rear Wheel Suspension, Shafts &
Axle
-Axle beam bushings
removing/installing 42.3 -Axle beam mounting bracket
installing 42.3 -Axle mounting
repairing 42.4
Rear Wheel Suspension, Shafts & Axle (cont'd)
-Cover ring
installed position 42.9 -Grease cap
removing/installing 42.8 -Rear axle
assembly 42.2
installing 42.4 -Seal
installing 42.10 -Stub axle/disc brake
assembly 42.7 -Support
installed position 42.6 -Suspension strut
assembly 42.5
removing/installing 42.4 -Wheel bearing
outer races
installing 42.9
-Wheel bearing play
adjusting 42.9

S

Seat belts
see Body Accessories-Interior
Spark plugs
see Ignition System
Starter
see Electrical- Battery, Starter Generator
Steering
-Adaptor sleeve removing/installing 48.5
-Auxiliary cooling line routing 48.20
-Lock cylinder removing/installing 48.5
-Power steering gear adjusting TRW 48.9
ZF 48.15
assembly TRW 48.7
ZF 48.13
removing/installing 48.11
universal joint shaft and pinion modifications 48.5a
-Power steering pump assembly 48.17 pressure
checking (4-cyl. engine) 48.10 checking (6-cyl. engine) 48.16
-Power steering system assembly 48.18 cleaning 48.6 pressure
checking 48.10 troubleshooting 48.21
-Steering column assembly 48.2, 48.4 length
checking 48.3
-Tie rod removing/installing 48.12
Struts
see Front Wheel Suspension-Shafts and Axle
Supercharger
-G-charger
boost pressure 21-30
component layout 21-10
damage
repairing 21-40
-Safety precautions chart 21-20
Sunroof
-Electrical cable drive checking/adjusting 60.6
-Parallel alignment checking/adjusting 60.4
-Slide/tilt sunroof assembly 60.2
assembly frame
installing 60.9
assembly frame removing 60.7
installing 60.4
removing 60.3
-Sunroof panel adjusting 60.6
headliner trim frame
removing 60.5
-Water drain hoses cleaning 60.10
Suspension
see Front Wheel Suspension-Shafts and Axle and Rear Wheel Suspension-Shafts and Axle

T

Thermostat
see Engine-Cooling System
Tires
see Wheels, Tires, Wheel Alignment
Torque Converter
096 automatic transmission
-Torque converter identification 32.10
removing/installing 32.20
seal, replacing 32.30
Trim-Interior
-Cassette storage box removing 70.8
-Door trim panel assembly 70.12
grab handle outer cover
removing/installing 70.13
-Front storage trays removing 70.7
-Glove box assembly 70.9 lid
removing/installing 70.10
lock cylinder 70.10
removing/installing 70.10
-Instrument panel installing 70.8
removing 70.7
trim plate, removing 70.8
-Molded headliner
installing 70.5
removing 70.3
-Plastic moisture barrier
replacing/installing 70.11
-Rear side trim panel
assembly 70.6

V

Valves
See Engine-Cylinder Head, Valve Drive

W

Windshield
See Glass, Window Regulators
Wheels, Tires, Wheel Alignment
-Front wheel camber adjusting 44.4, 44.4a
-Rear wheel toe determining 44.3
-Snow tires size 44.9
-Vibrations eliminating 44.5
-Wheel alignment
data (4 cylinder) 44.2
data (6 cylinder) 44.2a
Water pump
See Engine-Cooling System
Wiring Diagrams General information
-Cautions and warnings 3
-Handling components and connectors 15
-How to read wiring diagrams 5
-Test equipment 9
computer memory saver 14
LED test light 9
multimeter or volt/ohm meter 11
test kits 13
-Troubleshooting 17
basic electricity 17
checking for short circuit to ground 27
checking for voltage 20
checking ground connections 21
checking wiring and components 23
Main wiring diagrams
-1990 29
-1991 57
-1992
engine code PG 57 engine code AAA 83
Wiring Diagrams (cont'd) Main wiring diagrams (cont'd)
-1993
production up to Jan. 1993 83
production from Jan.1993 to Sept. 1993 113
-1994
production from Sept. 1993 to Mar. 1994 see Supplement
production from Mar. 1994 145 Auxiliary wiring diagrams
-Air conditioning
1990, 1991 177
1992 (engine code PG) 177 1992 (engine code AAA) 181
1993 (production up to Aug. 1992) 181
1993 (production from Aug. 1992) 185
1994 (production from Aug. 1993) see Supplement
-Anti-lock brake system (ABS)
1990 191 1991 195
1992 (engine code PG) 195 1992 (engine code AAA) 199 1993 199
1994 with electronic differential lock (EDL) 327
--Anti-theft alarm system
1991 205 1992 205
1993 (production up to Aug. 1992) 205 1993 (production from Aug. 1992) 209
1994 209
-Automatic shoulder belt system 1990 213
1991 217
1992 (engine code PG) 217 1992 (engine code AAA) 221 1993,1994 221
-Automatic transmission
1991 225
1992 (engine code PG) 225 1992 (engine code AAA) 231
1993 (production up to Jan. 1993) 231 1993
(production from Jan. 1993) 237 1994
(production up to Mar. 1994) 237 1994 (production from Mar. 1994) 243
-Central locking
1990 291 1991 297
1992 (engine code PG) 297 1992 (engine code AAA) 303
1993 (production up to Aug. 1992) 303
1993 (production from Aug. 1992) 307
1994 307
-Cruise control
1990 249 1991 251
1992 (engine code PG) 251
1992 (engine code AAA) 253
1993, 1994 253
-Daytime driving lights (Canada only) 1990 255
1991 and later 259
-Electronic engine controls
(Digifant I, California only)
1991, 1992 (engine code PG) 263
-Fuel pump
1990 (production from Sept. 1989) 269
-Heated seats
1990,1991 271
1992 (engine code PG) 271
1992 (engine code AAA) 273
1993,1994 273
-Headlight washers (Canada only) 1993, 1994 275
-Multi-function indicator 1991-1994
(production from Aug. 1990) 277
-Power mirrors
1992-1994 (engine code AAA) 283
-Power sunroof
1990 325 1991 285
1992 (engine code PG) 285 1992 (engine code AAA) 287
1993 (production up to Aug. 1992) 287
1993 (production from Aug. 1992) 289
1994 289
-Power windows
1990 291 1991 297
1992 (engine code PG) 297 1992 (engine code AAA) 303
1993 (production up to Aug. 1992) 303
1993 (production from Aug. 1992) 307 1994 307
-Radio, stereo
1990 315 1991,1992 319 1993 323
1994 see Supplement
-Radio with CD changer
see Supplement
-Recaro power seats (Canada only)
1992-1994 (engine code AAA) 311
-Seatbelt warning system (Canada only) 1990-1994 313

The Digifant engine management system is an electronicengine control unit (ECU), which monitors and controls the fuel injection and ignition systems in petrol engines, designed by Volkswagen Group, in cooperation with Robert Bosch GmbH.

Digifant is the outgrowth of the Digijet fuel injection system first used on water-cooled VolkswagenA2 platform-based models.

History[edit]

Digifant was introduced in 1986 on the 2.1 litreVolkswagen Type 2 (T3) (Vanagon in the US) engine. This system combined digital fuel control as used in the earlier Digi-Jet systems with a new digital ignition system. The combination of fuel injection control and ignition control is the reason for the name 'Digifant II' on the first version produced. Digifant as used in Volkswagen Golf and Volkswagen Jetta models simplified several functions, and added knock sensor control to the ignition system. Other versions of Digifant appeared on the Volkswagen Fox, Corrado, Volkswagen Transporter (T4) (known as the Eurovan in North America), as well as 1993 and later production versions of the rear-engined Volkswagen Beetle, sold only in Mexico. Lower-power versions (without a knock sensor), supercharged, and 16-valve variants were produced. Nearly exclusive to the European market, Volkswagen AG subsidiaryAudi AG also used the Digifant system, namely in its 2.0 E variants of the Audi 80 and Audi 100.

Digifant is an engine management system designed originally to take advantage of the first generation of newly developed digital signal processing circuits. Production changes and updates were made to keep the system current with the changing California and federal emissions requirements. Updates were also made to allow integration of other vehicle systems into the scope of engine operation.

Changes in circuit technology, design and processing speed along with evolving emissions standards, resulted in the development of new engine management systems. These new system incorporated adaptive learning fuzzy logic, enhanced and expanded diagnostics, and the ability to meet total vehicle emissions standards.

Features[edit]

Fuel injection control is digitally electronic. It is based on the measurement engine load (this signal is provided by the Air Flow Sensor), and on engine speed (signal provided by the Hall sender in the distributor). These primary signals are compared to a 'map', or table of values, stored in the Engine Control Module (ECM) memory.

The amount of fuel delivered is controlled by the duration of actuation of the fuel injector(s). This value is taken from a programme in the ECM that has 16 points for load and 16 points for speed. These 256 primary values are then modified by coolanttemperature, intake air temperature, oxygen content of the exhaust, car battery voltage and throttle position - to provide 65,000 possible injector duration points.

Digifant is unlike the earlier CIS and CIS-E fuel injection systems that it replaced, in that fuel injectors are mounted on a common fuel rail. CIS fuel injection systems used mechanical fuel injectors. The fuel injectors are wired in parallel, and are supplied with Constant System Voltage. The ECM switches the earth/ground on and off to control duration. All injectors operate at the same time (simultaneously, rather than sequentially) each crankshaft revolution; two complete revolutions being needed for each cylinder to receive the correct amount of fuel for each combustion cycle.

Ignition system control is also digital electronic. The sensors that supply the engine load and engine speed signals for injector duration provide information about the basic ignition timing point. The signal sent to the Hall control unit is derived from a programme in the ECM that is similar to the injector duration programme.

Engine knock control is used to allow the ignition timing to continually approach the point of detonation. This is the point where the engine will produce the most motive power, as well as the highest efficiency.

Additional functions of the ECM include operation of the fuel pump by closing the Ground for the fuel pump relay, and control of idle speed by a throttle plate bypass valve. The Idle Air Control Valve (IACV) (previously known as an Idle Air Stabiliser Valve - IASV), receives a changing milliamp signal that varies the strength of an electromagnet pulling open the bypass valve.

Idle speed stabilisation is enhanced by a process known as Idle Speed Control (ISC). This function (previously known as Digital Idle Stabilization), allows the ECM to modify ignition timing at idle to further improve idle quality.

Digifant II inputs/outputs[edit]

The 25 pin electronic control unit used in the Golf and Jetta receives inputs from the following sources:

• Hall sender unit (provides engine speed signal)
• Air Flow Sensor (provides engine load information)
• Coolant temperature sensor
• Intake Air Temperature sensor
• Knock sensor

Additional signals used as inputs are:

• Air conditioner (compressor on)
• Car battery voltage
• Starter motor signal

The Anti-lock Braking System (ABS), three-speed automatic transmission, and vehicle speed sensor are not linked to this system.

Outputs controlling engine operation include signals to the following:

• Fuel injectors
• Idle Air Control Valve
• Hall control unit
• Fuel pump relay
• Oxygen sensor heater

Additional systems[edit]

The evaporative emission system is controlled by a vacuum-operated mechanical carbon canistercontrol valve. Fuel pressure is maintained by a vacuum operated mechanical fuel pressure regulator on the fuel injector rail assembly. Inputs and outputs are shown in the following illustration. Digifant II as used on Golf and Jetta vehicles provides the basis for this chart.

North America variants[edit]

In North America, Volkswagen released two other versions of the Digifant fuel injection system (in addition to standard Digifant II described above).

A limited number of 1987-1990 California Golf and Jetta models are equipped with Digifant II that features an on-board diagnostics system (OBD). These vehicles have 'blink code' capacity to store up to five Diagnostic Trouble Codes (DTCs). Diagnostic troubleshooting is done by pressing the Check Engine switch on the dashboard. This system can also have carbon monoxide (CO), ignition timing and idle speed adjusted to baseline values.

In 1991, California Golf, Jetta, Fox, Cabriolet and Corrado vehicles were equipped with expanded OBD capabilities. This version was renamed 'Digifant I'. These later Digifant versions have 38-pin ECMs with Rapid Data Transfer and permanent DTC memory. All Eurovans with Digifant also have rapid data transfer and permanent DTC memory. These systems use a throttle plate potentiometer to track throttle plate position in place of the idle and full throttle switches used on earlier systems.

Another characteristic of Digifant II equipped vehicles in California is a switch mount on the dashboard which has a 'Check Engine' symbol. Digifant I models in California feature a Check Engine light, with the display of codes done by a special Volkswagen tool under the shift boot, or by a jumper and an LED by the home mechanic.

Digifant Reliability[edit]

Vehicles using engines equipped with Digifant fuel injection typically operated both efficiently and smoothly when new but suffered from a number of issues as the car aged, even by a few months. Digifant sensors & other components, especially the ECU itself, were remarkably sensitive to poor electrical grounding. Without a reliable ground signal to reference, the system was vulnerable to errors and malfunction. In the 1980s and 1990s many Volkswagen / Audi designs did not incorporate sufficient engine compartment grounding, and when the car's engine compartment became soiled with dirt, oil & road salts from several months / years of use, the fuel injection system would fail in often inexplicable ways. Backfiring, stalls & other poor running were all too common. Later versions were improved by providing multiple grounding paths, but the early Digifant systems suffered poor service reputations.

Most of driveability issues can be traced back to a few issues:

• Bad ECM earth/ground
• Bad o2/lambda sensor earth/ground
• Faulty Engine Coolant Temperature sensor (ECT)

The engine coolant temperature sensor is located in the coolant flange,(under the distributor on the Polo Fox Coupe) on the front of the cylinder head (on transverse-engine vehicles). The bad earth/ground can be traced to an essential ground strap on the front upper transmission bolt. Without this, the ECU tends to earth/ground elsewhere, causing a specific trace to burn out on the circuit board and killing the ECU. This causes the injectors to stay open constantly, flooding the engine.

Common issues that indicate a failed engine coolant temperature sensor are:

• Vehicle idles poorly
• Engine sputters, might stall
• Higher than normal fuel consumption

The part number for this sensor is '025 906 041 A' (always check with your Volkswagen dealer for the most updated part number). The resistance of this unit is approximately 3.2 Kohm at 10 degrees C. If it measures open circuit this will explain erratic idle and throttle speeds especially when the engine is cold.

When replacing this sensor, it is important to also replace the clip that holds it in position ('032 121 142') and the O-ring ('N 903 168 02').

Once the new sensor has been installed, start the engine and disconnect the blue coolant temperature sensor. Rev the engine through 3,000 rpm three times, each time allowing the throttle to close completely. This clears the Digifant ECM fault memory.

See also[edit]

References[edit]

• Robert Bentley. Volkswagen GTI, Golf, Jetta Service Manual 1985 through 1992. Cambridge: Bentley Publishers, 1992.
• Volkswagen of America. 'Digifant Engine Management'. Engine Management Systems. Auburn Hills: Volkswagen Service Publications, 2006. 31–36.

External links[edit]