VOLKSWAGEN CORRADO 1990 Repair Manual

ABBREVIATIONS
Article Text (p. 12)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PM³Trans. ³Transaxle/Transmission ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ "V" ABBREVIATION TABLE
"V" ABBREVIATION TABLE
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ABBREVIATION
³DEFINITION ³
ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´
³V
³Valve ³
³VAF
³Vane Air Flow sensor or circuit ³
³VAPS
³Variable Assist Power Steering ³
³VAT
³Vane Air Temperature ³
³VATS
³Vehicle Anti-Theft System ³
³VBATT
³Vehicle Battery Voltage ³
³VCC
³Viscous Converter Clutch ³
³VIN
³Vehicle Identification Number ³
³VIO
³Violet ³
³VLR
³Volt Loop Reserve ³
³VM
³Vacuum Modulator ³
³VM
³Vane Meter ³
³VOM
³Volt-Ohmmeter (Analog) ³
³VPWR
³Vehicle Power supply voltage (10-14 volts) ³
³VREF
³Voltage Reference (ECA supplied reference voltage ³
³VRV
³Vacuum Regulator Valve ³
³VSC
³Vehicle Speed Control sensor or signal ³
³VSS
³Vehicle Speed Sensor or signal ³
³VSV
³Vacuum Switching Valve ³
³Vac.
³Vacuum ³
³Volt.
³Voltage ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ "W" ABBREVIATION TABLE
"W" ABBREVIATION TABLE
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ABBREVIATION
³DEFINITION ³
ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´
³W/
³With ³
³W/O
³Without ³
³WAC
³WOT A/C Cut-off switch or circuit ³
³WAC
³Wide Open Throttle A/C Switch ³
³WHT
³White ³
³WOT
³Wide Open Throttle ³
³YEL
³Yellow ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙEND OF ARTICLE

ALTERNATOR & REGULATOR - BOSCH
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PM
ARTICLE BEGINNING
1989-92 ELECTRICAL
Alternators & Regulators - Bosch
Cabriolet, Fox, Golf, GTI, Jetta, Jetta GLI, Vanagon
1991 Corrado, Passat & Golf GL
NOTE: Some Golf, GTI, Jetta and Jetta GLI models may use a
Motorola alternator. Please refer to ALTERNATORS - SEV
MOTOROLA article. Vanagon models only use Bosch 90-amp
alternators.
DESCRIPTION
Bosch alternators are conventional 3-phase, self-rectifying
type alternators. Bosch 65 through 75-amp alternators use 3 positive
and 3 negative diodes connected to stator windings to rectify current.
Bosch 90-amp alternators use 14 diodes.
All alternators use 3 exciter diodes connected to stator
windings. These diodes turn off the alternator indicator light and
supply power to the voltage regulator while the engine is running.
Bosch regulators are transistorized and integral with alternator.
BELT TENSION ADJUSTMENT
BELT TENSION SPECIFICATIONSÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication (1) Deflection In. (mm)
New Belt ................................... 5/64 (2)
Used Belt ................................. 13/64 (5)
(1) - Deflection is with 22 lbs. (10 kg) pressure
applied midway on longest belt run.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ TESTING (ON-VEHICLE)
WIRING CONTINUITY TEST
1) Connect a voltmeter between alternator "B+" terminal and
ground. Voltmeter should indicate battery voltage. If not, check
wiring between alternator and battery.
2) Turn ignition on and ensure alternator indicator light
comes on. If light does not come on, check wiring between alternator
and warning light, including indicator bulb.
OUTPUT TEST
1) Ensure connections at battery, alternator, and starter

ALTERNATOR & REGULATOR - BOSCH
Article Text (p. 2)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PM
(most vehicles) are clean and tight. Ensure alternator, engine and
body are properly grounded. Ensure alternator drive belt is tight and
in good condition.
2) Connect ammeter following manufacturer's instructions.
Connect voltmeter leads to battery terminals. Adjust carbon pile on
tester until voltmeter reads 13.5 volts. Alternator output should be
28-35 amps.
3) Repeat process at 1000 RPM. Alternator output should be
75-85 amps. Repeat test at 2000 RPM. Alternator output should be 89
amps. If alternator output is low, remove alternator for testing and
repairs.
4) Start engine and run at 3000 RPM. Adjust carbon pile on
tester to obtain maximum alternator output. Do not allow voltage to go
below 12.6 volts.
5) Alternator output should equal alternator rated output,
minus 16-20 amps. If reading is 16-20 amps below alternator rating,
replace regulator and retest. If output is still low, repair or
replace alternator.
REGULATOR CONTROL VOLTAGE TEST
1) Connect ammeter following manufacturer's instructions.
Connect voltmeter leads to battery terminals. Start engine and run at
3000 RPM.
2) Run engine until voltage stops rising. Voltage should be
13.5-14.5 volts. If reading is incorrect, remove regulator and ensure
brushes are longer than 7/32" (6 mm). Replace if necessary.
3) If brushes are okay and regulator fails to keep voltage
within specified limits, replace regulator and retest. If voltage is
still incorrect, repair or replace alternator.
BENCH TESTING
DIODE ASSEMBLY
1) Place ohmmeter on x 100 scale. Connect ohmmeter leads
across "B+" terminal and 3 stator terminals one at a time. Reverse
leads. Ohmmeter should indicate continuity in one direction only.
2) Connect ohmmeter leads across negative plate and 3 stator
terminals one at a time. See Fig. 1. Reverse leads. Ohmmeter should
indicate continuity in one direction only.
3) Connect ohmmeter leads across "D+" terminal and 3 stator
terminals one at a time. Reverse leads. Ohmmeter should indicate
continuity in one direction only. Replace diode assembly if defective.

ALTERNATOR & REGULATOR - BOSCH
Article Text (p. 3)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PMFig. 1: Bosch Diode Assembly Test
Courtesy of Volkswagen United States, Inc.
STATOR
1) Place ohmmeter on lowest scale. Connect ohmmeter across
stator leads. Resistance between leads should be approximately .14-.15
ohms for 55-amp alternator and .09-.10 ohms for 65 through 90-amp
alternators. If resistance is incorrect, stator has open or shorted
windings and must be replaced.
2) Place ohmmeter on X 1000 scale. Connect ohmmeter between
stator core and stator lead. No continuity should exist. If continuity
exists, stator is grounded and must be replaced.
ROTOR
1) Place ohmmeter on lowest scale. Connect ohmmeter across
slip rings. Resistance should be 2.8-3.1 ohms for 65 through 90-amp
alternators.
2) If resistance is too low, rotor has short circuit and must
be replaced. If resistance is infinity (no continuity), rotor has open
circuit and must be replaced.
3) Place ohmmeter on x 1000 scale. Connect ohmmeter between
either slip ring and rotor core. No continuity should exist. If
continuity exists, rotor is grounded and must be replaced.
4) Clean slip rings using fine sandpaper. Rings which are
worn or pitted should be turned on lathe. Minimum ring diameter is 1

ALTERNATOR & REGULATOR - BOSCH
Article Text (p. 4)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PM
1/16".
5) If slip rings are beyond repair, remove rear bearing from
slip ring end of rotor. Unsolder wires from slip rings and bend up
ends of rotor winding. Pull off slip rings. Ensure ends of rotor
winding are not damaged.
6) Insert ends of rotor winding into slip ring and press new
slip ring onto rotor. Slip ring end must be 9/64" from end of collar.
Solder rotor winding to slip ring terminals. Turn rings on lathe and
retest rotor. Maximum slip ring run-out is .0012" (.03 mm).
BEARINGS
Always replace bearings. If replacement front bearing is
sealed on one side only, open side must face rotor. If replacement
rear bearing is sealed on one side only, open side must face away from
rotor.
BRUSHES
Ensure brushes are longer than 7/32". Replace if necessary.
Unsolder brushes from voltage regulator. Solder new brushes. Do not
allow solder to run into strands of brush leads. Brushes must be free
to slide in brush holder with normal spring tension of 10-14 ozs.
(283-397 g).
OVERHAUL
For alternator disassembly and reassembly, refer to Fig. 2.Fig. 2: Exploded View of Typical Bosch Alternator
Courtesy of Volkswagen United States, Inc.

ALTERNATOR & REGULATOR - BOSCH
Article Text (p. 5)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PM
END OF ARTICLE

ANTI-LOCK BRAKE SAFETY PRECAUTIONS
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PM
ARTICLE BEGINNING
GENERAL INFORMATION
Anti-Lock Brake Safety Precautions
* PLEASE READ THIS FIRST *
This article is intended for general information purposes
only. This information may not apply to all makes and models. If
vehicle is equipped with Anti-Lock Brake System (ABS), refer to
appropriate ANTI-LOCK BRAKE SYSTEM article in the BRAKES section for
description, operation, depressurizing, testing, system bleeding,
trouble shooting and servicing of specific system.
WARNING: Failure to depressurize ABS could lead to physical injury.
ANTI-LOCK BRAKE SAFETY PRECAUTIONS
WARNING: Failure to depressurize ABS could lead to physical injury.
* NEVER open a bleeder valve or loosen a hydraulic line
while ABS is pressurized.
* NEVER disconnect or reconnect any electrical connectors
while ignition is on. Damage to ABS control unit may result.
* DO NOT attempt to bleed hyudarulic system without first
referring to the appropriate ANTI-LOCK BRAKE SYSTEM article
in the BRAKES section.
* Only use specially designed brake hoses/lines on ABS equipped
vehicles.
* DO NOT tap on speed sensor components (sensor, sensor rings).
Sensor rings must be pressed into hubs, NOT hammered into
hubs. Striking these components can cause demagnetization or
a loss of polarization, affecting the accuracy of the speed
signal returning to the ABS control unit.
* DO NOT mix tire sizes. Increasing the width, as long as tires
remain close to the original diameter, is acceptable. Rolling
diameter must be identical for all 4 tires. Some
manufacturers recommend tires of the same brand, style and
type. Failure to follow this precaution may cause inaccurate
wheel speed readings.
* DO NOT contaminate speed sensor components with grease. Only
use recommended coating, when system calls for an
anti-corrosion coating.
* When speed sensor components have been removed, ALWAYS check
sensor-to-ring air gaps when applicable. These specifications
can be found in each appropriate article.
* ONLY use rocommended brake fluids. DO NOT use silicone brake
fluids in an ABS equipped vehicle.
* When instlling transmittion devices (CB's, telephones, etc.)
on ABS equipped vehicles, DO NOT locate the antenna near the
ABS control unit (or any control unit).

ANTI-LOCK BRAKE SAFETY PRECAUTIONS
Article Text (p. 2)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PM
* Disconnect all on-board computers, when using electric
welding equipment.
* DO NOT expose the ABS control unit to prolonged periods of
high heat (185 øF/85øC for 2 hours is generally considered a
maximum limit).
END OF ARTICLE

ANTI-LOCK BRAKE SYSTEM
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PM
ARTICLE BEGINNING
1990-92 BRAKES
Volkswagen Anti-Lock Brake System
Corrado, Jetta, Passat
DESCRIPTION
All models use a Teves Anti-Lock Brake System (ABS). See
Fig. 1. This system reduces the chance of wheel lock-up during heavy
braking. The system consists of 4 wheel speed sensors, Electronic
Control Unit (ECU), hydraulic modulator/pump and solenoid valves,
ANTI-LOCK warning light and BRAKE warning light. There are 2 relays
located at fuse/relay panel, to protect the hydraulic modulator and
ECU.
NOTE: For more information on brake system, see appropriate BRAKE
SYSTEM article.
OPERATION
When pressure is applied to brake pedal, the ECU monitors
input signals from each wheel speed sensor. If ECU measures a rate of
reduction greater than what is programmed in ECU, the ECU will output
a signal to appropriate solenoid valve. Each solenoid valve allows
hydraulic pressure to increase or decrease to the appropriate wheel
cylinder.
If a system failure occurs, the ANTI-LOCK warning light,
located on instrument panel, will come on. System will be deactivated,
but conventional brake system will still operate. If brake fluid level
drops too low, BRAKE warning light, located on instrument panel, will
come on.
ANTI-LOCK BRAKE SAFETY PRECAUTIONS
* NEVER open a bleeder valve or loosen a hydraulic line while
ABS is pressurized,
* NEVER disconnect or reconnect any electrical connectors while
ignition is on. Damage to ABS control unit may result.
* Only use specially designed brake hoses/lines on ABS equipped
vehicles.
* DO NOT tap on speed sensor components (sensor, sensor rings).
Speed rings must be pressed, NOT hammered into hubs. Striking
these components can cause demagnetization or a loss of
polarization, affecting the accuracy of the speed signal
returning to the ABS control unit.
* DO NOT mix tire sizes. Increasing the width, as long as tires
remain close to the original diameter, is acceptable. Rolling
diameter must be identical for all 4 tires (and spare tire
also). Some manufacturers recommend tires of the same brand,

ANTI-LOCK BRAKE SYSTEM
Article Text (p. 2)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:42PM
style and type. Failure to follow this precaution may cause
inaccurate wheel speed readings.
* DO NOT contaminate speed sensor components with grease. Only
use recommended anti-corrosion coating.
* When speed sensor components have been removed, ALWAYS check
sensor-to-ring gap when applicable. These specifications can
be found in WHEEL SPEED SENSOR under ADJUSTMENTS.
* ONLY use recommended brake fluids. DO NOT use silicone brake
fluids in an ABS equipped vehicle.
* When installing transmitting devices (CB's, telephones, ect.)
on ABS equipped vehicles, DO NOT locate antenna near the ABS
control unit or any control unit.
* Disconnect all on-board computers when using electric welding
equipment.
* DO NOT expose the ABS control unit to prolonged periods of
high heat (185øF/85øC for 2 hours is generally considered a
maximum limit).
CAUTION: The ABS system is under extremely high pressure.
Depressurize the brake system before loosening or removing
any hydraulic component.
DEPRESSURIZING BRAKE SYSTEM
Turn ignition off. Depress and release brake pedal 25-35
times, or until there is a noticeable increase in the effort to
depress the brake pedal. Do not turn ignition on until all hydraulic
lines and components are fully tighten.
BLEEDING BRAKE SYSTEM
FRONT BRAKES
Depressurize brake system. See DEPRESSURIZING BRAKE SYSTEM.
Connect a container with hose to left front bleeder screw. Have
assistant depress and release brake pedal a few times. Holding brake
pedal down, open bleeder screw and allow fluid to enter container.
Close bleeder screw and then release brake pedal. Continue this method
until no air is present in fluid. Check master cylinder fluid level to
make sure it does not go below minimum level mark. Use same procedure
for right front brake.
REAR BRAKES
CAUTION: When bleeding rear brakes, accumulator pressure (about 3100
psi) is used to assist in procedure. Use eye protection
when performing this procedure. DO NOT allow pump to run
longer than 2 minutes. See ANTI-LOCK BRAKE SAFETY
PRECAUTIONS in this article.
Attach hose and container to right rear bleeder screw.
Position actuator lever on load-sensing pressure regulator toward rear