boot VOLKSWAGEN CORRADO 1990 Workshop Manual

D - ADJUSTMENTS
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 09:43PM
NOTE: Mixture adjustment is NOT a part of normal tune-up procedure
and should not be performed unless mixture control unit is
replaced or vehicle fails emissions testing.
NOTE: Ensure system pressure is correct before attempting idle
speed or mixture adjustment.
IDLE SPEED & MIXTURE ADJUSTMENT
FOX (CIS-E) & JETTA GLI 2.0L (CIS-MOTRONIC)
1) Ignition timing and idle speed must be checked before CO
is adjusted. See CHECKING & ADJUSTING under IGNITION TIMING. With
ignition timing properly adjusted, check and adjust idle speed,
differential pressure regulator current and idle mixture. Repeat the
adjustments until all occur at the same time.
2) Warm engine to normal operating temperature. Radiator fan
must come on at least once and engine oil temperature must be at least
176øF (80øC). Turn off all electrical equipment, including A/C and
radiator fan. Disconnect all fuel pressure test equipment (if
installed). If injection lines have been removed or replaced, run
engine several times to 3000 RPM for about 2 minutes.
3) Ensure idle switch is properly adjusted. Check that
auxiliary air regulator valve is fully closed. Pinch shut the hose
leading from the idle speed boost valve(s). Remove temperature sensor
harness connector from the temperature sensor. Pull crankcase breather
hoses off valve cover and air filter, vent to atmosphere.
4) Remove suction hose from carbon canister. Disconnect "T"
fitting from carbon canister at air intake boot. On Fox models only,
remove connector from coolant temperature sensor and install 15,000-
ohm resistor (VW 1490) on temperature sensor harness. See Fig. 1.Fig. 1: Fox Coolant Temperature Sensor Location & 15,000-Ohm Test
Resistor
Courtesy of Volkswagen United States, Inc.
5) Turn "T" fitting 90 degrees and insert blank side with .

D - ADJUSTMENTS
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 09:43PM
059" (1.5 mm) restrictor into hole in intake air boot. If vehicle is
not equipped with this type of connector, use Plug (026 133 382D) with
.059" (1.5 mm) orifice. Adjust idle speed if not within specification.
See IDLE SPEED & CO LEVEL table.
6) Connect fuel pressure gauge and ensure system fuel
pressure is correct. See FUEL SYSTEM in F - BASIC TESTING article.
Connect an inductive tachometer or Tester (VW 1367) and Test Lead (VW
1473). See Fig. 2.Fig. 2: Tester (VW 1367) & Test Lead (VW 1473)
Courtesy of Volkswagen United States, Inc.
7) Remove CO probe receptacle cap and connect CO meter.
Ensure fit is snug to prevent exhaust leaks. Connect Digital
Multimeter (US 1119) with Adapter (VW 1315 A/1) to differential
pressure regulator. See Fig. 3.Fig. 3: Digital Multimeter Hook-Up
Courtesy of Volkswagen United States

D - ADJUSTMENTS
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 09:43PM
8) Connect adapter between connector and regulator. Connect
multimeter to adapter and turn switch to DCA 200 milliamp-range. Read
and compare current (4-16 milliamps) and CO values to specifications.
Turn engine off.
9) If CO reading is more than 1.2% at current reading of 4-16
milliamps, check for exhaust system leaks, ignition timing, injector
inserts for leaks, and fuel distributor for uneven fuel distribution.
If required, seal injector inserts with sealing compound and tighten
to 15 ft. lbs. (20 N.m).
10) If current reading is less than 4 milliamps or more than
16 milliamps, adjustment must be made with CO adjustment screw as
follows: remove boot from mixture control unit. Center punch hole in
CO adjusting hole and drill a 3/32" hole to a depth of 5/32" (4 mm).
DO NOT drill completely through as adjustment screw will be damaged.
11) Install a 1/8" sheet metal screw and remove plug using
pliers. Start engine and run at idle. Adjust current reading to 10
milliamps by turning CO adjustment screw with Wrench (P 377). Turn
screw clockwise to lower reading, counterclockwise to raise reading.
See Fig. 4.Fig. 4: Adjusting Idle CO (CIS-E)
Courtesy of Volkswagen United States, Inc.
12) Readjust idle speed if required. Turn engine off. Install
new plug in mixture control unit and seat plug flush with unit. Remove
all test equipment and reconnect all hoses and wiring.
CABRIOLET, CORRADO, GOLF GL/GTI 1.8L & JETTA (DIGIFANT II)
1) For correct system operation the basic adjustments to
ignition timing, CO content and idle speed must be correct. These
adjustments are inter-related and must be checked/adjusted together.
2) Warm engine to normal operating temperature (radiator fan
should have cycled at least once). Engine oil temperature must be at
least 176øF (80øC). All electrical components must be off. Ensure idle
speed stabilization system is okay (with ignition on idle stabilizer
valve must hum/buzz). Ensure throttle valve switch is adjusted
correctly.

F - BASIC TESTING
Article Text (p. 8)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
Fox
Coil Wire With Connectors .................... 1600-2400
Spark Plug Wire With Connectors .............. 4800-7200
Spark Plug Connector ......................... 4000-6000
Suppressor .................................... 800-1200ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ IGNITION COIL RESISTANCE TABLE
IGNITION COIL RESISTANCE TABLE - Ohms @ 68
øF (20øC)
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Primary Secondary
Jetta GLi 2.0L ......... .60-.70 ............. 6500-8500
All Other Models ....... .52-.76 ............. 2400-3500
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ DISTRIBUTOR
HALL EFFECT SENDER
1) Remove coil secondary and attach to ground. Disconnect
Hall Effect sender harness connector at distributor. Using a LED Test
Light (US 1115), check for voltage between outer terminals of
connector. See Fig. 5. With ignition on, light should be on. If not,
check wiring for short or open circuit. If wiring is okay, replace
Digifant control unit.
2) If light came on in step 1), reconnect Hall Effect sender
harness connector. Pull back Hall Effect sender boot to expose contact
terminals. Apply LED Test Light (US 1115) probe to center contact and
battery positive terminal. See Fig. 5. Observe test light while
cranking engine. If test light blinks, Hall Effect sender is okay. If
not, replace Hall Effect sender.Fig. 5: Testing Typical Hall Effect Sender
Courtesy of Volkswagen United States, Inc.
ELECTRONIC CONTROL UNIT (ECU)

F - BASIC TESTING
Article Text (p. 11)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PMFig. 8: Testing Typical Hall Effect Sender Connector
Courtesy of Volkswagen United States, Inc.
HALL EFFECT SENDER SWITCHING FUNCTION
1) Peel back the protective rubber boot on the Hall Effect
sender harness connector. Remove coil secondary and attach to ground.
Disconnect Hall Effect sender wire harness connector at distributor.
Using a LED Test Light (US 1115), check for voltage between outer
terminals of connector. See Fig. 5 or 8. With ignition on, light
should be on. If not, check wiring for short or open circuit. If not,
replace ignition control unit.
2) If light came on in step 1), reconnect Hall Effect sender
harness connector. Pull back Hall Effect sender boot to expose contact
terminals. Apply LED Test Light (US 1115) probe to center contact and
battery positive terminal. See Fig. 5 or 8. Observe test light while
cranking engine. If test light blinks, Hall Effect sender is okay. If
not, replace Hall Effect sender.
CIS-MOTRONIC (ECU) RESPONSE TO HALL EFFECT SENDER SIGNAL
1) Ground the ignition coil secondary lead. Remove coil
power stage connector and connect a LED test light (US 1115) between
terminals No. 2 and No. 3. See Fig. 7.
2) Actuate the starter, the test light should flicker. If
not, check for open wire between terminal No. 2 of the power stage
connector and terminal No. 11 of the ECU, or ECU is defective. Repair
wiring or replace ECU and recheck.
POWER STAGE RESPONSE TO CIS-MOTRONIC (ECU) SIGNAL
1) Reconnect the coil power stage connector, then disconnect
the Hall Effect sender connector and attach a voltmeter to terminal

F - BASIC TESTING
Article Text (p. 13)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
DISTRIBUTOR
HALL EFFECT SENDER
1) Remove coil secondary and attach to ground. Disconnect
Hall Effect sender wire at the distributor. Using a LED Test Light (US
1115), check for voltage between outer terminals of connector. See
Fig. 5 or 8. With ignition on, light should be on. If not, check
wiring for short or open circuit. If wiring is okay, replace Digifant
control unit.
2) If light came on in step 1), reconnect Hall Effect sender
harness connector. Pull back Hall Effect sender boot to expose contact
terminals. Apply LED Test Light (US 1115) probe to center contact and
battery positive terminal. See Fig. 5. Observe test light while
cranking engine. If test light blinks, Hall Effect sender is okay. If
not, replace Hall Effect-sender.
IDLE SPEED, CO LEVEL & IGNITION TIMING
Ensure idle speed, CO level and base ignition timing are set
to specification. If necessary, see ON-VEHICLE ADJUSTMENTS article.
IDLE SPEED & CO LEVEL TABLEÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Idle RPM CO Level %
All Models ............ 800-1000 .............. 0.3-1.2%
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄIGNITION TIMING TABLE (Degrees BTDC @ RPM)
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Checking Adjusting
1.8L ............... 4-8 @ 2250-2350 . 5-7 @ 2250-2350
2.0L ................ 4-8 @ 770-830 ...... 5-7 @ 770-830
2.1L (1) ........... 4-8 @ 2250-2350 . 5-7 @ 2250-2350
(1) - With coolant temperature sensor disconnected.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ SUMMARY
If no faults were found while performing F - BASIC TESTING,
proceed to H - TESTS W/CODES article for diagnosis by symptom (i.e.,
ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.
END OF ARTICLE

HEATER SYSTEM
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 09:45PM
retaining screws. Remove lower left instrument panel. Remove lower
right instrument panel tray retaining screws.
2) Remove lower right instrument panel. Remove gearshift
lever knob. Remove gearshift lever boot. Remove center console
retaining screws. Slide center console rearward. Disconnect electrical
connectors attached to center console. Remove center console.
3) Remove temperature control knobs. Remove trim plate.
Remove radio. Remove switches from instrument panel. Remove instrument
panel trim plate retaining screws. Remove instrument panel trim plate.
Remove instrument cluster retaining screws. Remove instrument cluster.
4) Disconnect speedometer cable, electrical connectors and
vacuum hoses from instrument cluster. Remove speaker grilles. Remove
air outlet grilles from housings. Remove housing retaining screws.
Remove air outlet housings. Remove instrument panel mounting nuts and
screws.
5) Remove instrument panel. Disconnect heater hoses from
heater core. Remove heater assembly mounting bolts and nuts. Remove
all attaching ducts. Disconnect cables from heater assembly. Remove
heater assembly.
INSTALLATION
Reverse removal procedure for installation. Fill radiator
with coolant and start engine. Ensure heater control is in warm
position to purge air from heater core.
WIRING DIAGRAMSFig. 4: Heater System Wiring Diagram (Cabriolet)Fig. 5: Heater System Wiring Diagram (Corrado)

I - SYSTEM/COMPONENT TESTS
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 09:46PM
circuits to ECU. The ECU engine ground is near ignition distributor.
Remove ECU connector. Check resistance to ground on terminal No. 35.
Resistance should be zero ohms. If resistance is not zero ohms, repair
open or short in wiring.
POWER CIRCUITS
Turn ignition off. Disconnect ECU connector. Using a
voltmeter, check terminals No. 12, 14, 19 and 34 for battery voltage.
If battery voltage is not present. Check fuses No. 15, 18 and 24. If
fuses are okay, check for open in wiring between ECU and fuse box. See
L - WIRING DIAGRAMS for terminal identification and wire colors.
ENGINE SENSORS & SWITCHES
AIRFLOW SENSOR (FOX & JETTA GLI)
1) Start engine to pressurized fuel system. Turn engine off
and remove intake boot from top of airflow sensor. Disconnect coil
secondary wire from coil and jumper to ground.
2) Check sensor play by slowly moving sensor plate through
travel range with a magnet. See Fig. 1. Resistance should be felt.
Move plate back to the rest position. There should be no resistance.
If binding is felt, loosen sensor plate hold-down bolt and adjust
plate to center of venturi.
3) If resistance is uneven, remove airflow sensor from
housing to clean and lubricate lever assembly. If resistance is caused
by control plunger, remove and clean control plunger assembly. If
binding continues, replace fuel distributor.
4) Check position of airflow sensor plate. Airflow sensor
plate edge must be within .075" (1.9 mm) below the narrowest section
of the venturi. If not, bend sensor spring until correct specification
is obtained. Ensure a small gap exists between sensor lever and
control plunger.Fig. 1: Identifying Airflow Sensor Components (Fox & Jetta GLi)
Courtesy of Volkswagen United States, Inc.
AIRFLOW SENSOR (GOLF & JETTA)
1) Start engine to pressurized fuel system. Turn engine off

I - SYSTEM/COMPONENT TESTS
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 09:46PM
and remove intake boot from top of airflow sensor. Check sensor plate
by lifting plate through travel cycle with magnet or pliers.
2) Continuous resistance should be felt. Move plate back to
rest position. There should be no resistance. If resistance is felt,
replace airflow sensor. If sensor plate lever is difficult to move
upward but moves freely downward, check sensor plate for correct
centering.
3) Sensor plate should be evenly centered in the housing with
plate edge at the narrowest section of the venturi while at rest
position. If sensor plate adjustment is correct, check control plunger
for sticking. If control plunger is sticking, replace fuel distributor
assembly.
AIRFLOW SENSOR (VANAGON)
1) Turn ignition off. Remove Electronic Control Unit (ECU)
connector. Attach ohmmeter to ECU connector. See Fig. 3. Resistance
should correspond to ECU PIN CHECK in AFC-DIGIFANT II AIRFLOW SENSOR
RESISTANCE table.
2) With ignition off, unplug connector from airflow sensor.
Attach ohmmeter to airflow sensor terminal. See Fig. 2. Resistance
should correspond to AIRFLOW SENSOR PIN CHECK in AFC-DIGIFANT II
AIRFLOW SENSOR RESISTANCE table.
AFC-DIGIFANT II AIRFLOW SENSOR RESISTANCEÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄTerminal Ohms
ECU Pin Check
No. 6 & No. 17 .......................................... 500-1000
No. 17 & No. 21 .............................................. (1)
Airflow Sensor Pin Check
No. 3 & No. 4 ........................................... 500-1000
No. 2 & No. 3 ................................................ (1)
(1) - Resistance should fluctuate as sensor door is moved.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄFig. 2: Identifying AFC-Digifant II Airflow Sensor & Terminals
Courtesy of Volkswagen United States, Inc.

I - SYSTEM/COMPONENT TESTS
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 09:46PM
COOLANT TEMPERATURE SENSOR
Turn ignition off. Use a thermometer to measure coolant
temperature. Unplug connector from Electronic Control Unit (ECU).
Attach an ohmmeter between terminals No. 6 and No. 10 of ECU
connector. See Fig. 3. Resistance should decrease as coolant
temperature increases. See COOLANT TEMPERATURE SENSOR RESISTANCE
table. Replace sensor if resistance is not within specification.
COOLANT TEMPERATURE SENSOR RESISTANCEÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄTemperature Ohms
68
øF (20øC) .............................................. 2200-2700
158
øF (70øC) ............................................... 400-480
194
øF (90øC) ............................................... 210-280
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄFig. 3: Identifying ECU Connector Terminals
Courtesy of Volkswagen United States, Inc.
HALL EFFECT SENDER
For Hall Effect sender testing, see F - BASIC TESTING
article.
OXYGEN SENSOR (ALL MODELS EXCEPT VANAGON)
1) Ensure exhaust system is not leaking. Warm engine to
normal operating temperature with all accessories off. Remove
differential pressure regulator connector. Connect Wiring Harness
Adapter (VW 1315 A/1) in series. See Fig. 4.
2) Attach Multimeter (US 1119) to adapter and set meter on
DCA 200m scale. Remove PCV hose and vent to atmosphere. Remove 90
degree "T" connector and insert port with small vent hole into intake
air boot. See Fig. 5.
3) Start engine and allow to run for 2 minutes. Meter reading
should start fluctuating. If reading does not fluctuate, raise engine
speed to 3000 RPM. If meter reading fluctuates, oxygen sensor is okay.
If reading still does not fluctuate, check control unit and wiring
harness for short or open circuit.
OXYGEN SENSOR (VANAGON)
1) Ensure pressure regulator is functional and engine is at
normal operating temperature. Start engine and allow to run for 2