Engine Controls - System/component Tests Audi Cabriolet I

INTRODUCTION

Before testing separate components or systems, perform preliminary inspection. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in TESTS W/CODES article.

Note. Testing individual components does not isolate shorts or opens. Perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance unless otherwise instructed in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.

ELECTRICAL COMPONENT LOCATIONS

Scheme 5

Scheme 6

Intake Manifold Change-Over (IMCO) Valve

1. Increase engine speed to more than 4100 RPM. If IMCO valve vacuum motor is actuated, system is okay. If IMCO valve vacuum motor is not actuated, disconnect electrical connector from IMCO valve control solenoid. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) .
2. Measure resistance across terminals of IMCO valve control solenoid. If resistance is not 25-35 ohms, replace IMCO valve control solenoid. If resistance is 25-35 ohms, apply battery voltage across terminals of IMCO valve control solenoid. Replace IMCO valve control solenoid if it does not operate. If IMCO valve control solenoid operates, check PCM and wiring.

A/C COMPRESSOR CUT-OUT SIGNAL

1. Ensure A/C operates, no DTCs are stored in PCM memory and vehicle temperature is 59°F (15°C) or greater. Start engine. On vehicles with automatic A/C, press AUTO button, LO temperature button and HI blower button. On vehicles with manual A/C, press A/C button.
2. On all vehicles, ensure compressor symbol comes on and A/C compressor runs. Enter ENGINE BASIC SETTING mode (display group 00). See «TESTS W/CODES»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-tests-wcodes) article. If A/C compressor stops, go to step 6).
3. If A/C compressor does not stop, turn A/C off. Leave engine idling. Enter READ MEASUREMENT BLOCK mode (display group 04). In display field 4, observe second digit of 4-digit display value (switch inputs). Disregard all other digits. With A/C off, zero should be displayed. With A/C turned on as in step 1), "1" should be displayed.
4. If displayed values are as specified, go to step 6). If displayed values are not as specified, ensure A/C-heater control panel settings are as specified.
5. If settings are as specified, check circuit between PCM and A/C clutch control module (manual A/C) or between PCM and A/C-heater control panel (automatic A/C). See the «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) . Repair circuit if faulty. If circuit is okay, repair A/C electrical system.
6. Quickly snap throttle open fully. Displayed value should briefly drop to zero and rise to "1" after accelerator pedal is released. If displayed value is not as specified, replace PCM. If displayed value is as specified, but A/C compressor did not shut off, repair A/C electrical system.

A/C COMPRESSOR ON SIGNAL

1. Enter READ MEASUREMENT BLOCK mode (display group 4). See «TESTS W/CODES»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-tests-wcodes) article. In display field 4, observe first digit of 4-digit display value (switch inputs).
2. Value should be zero. Disregard remaining digits. On vehicles with automatic A/C, press AUTO button, LO temperature button and HI blower button. On vehicles with manual A/C, press A/C button.
3. On all vehicles, if "1" is not displayed as first digit of 4-digit display, go to next step. If "1" is displayed, press right arrow button. Input 06 for END DATA TRANSMISSION and acknowledge with "Q" button. Turn ignition off. Connect Test Box (VAG 1598) to PCM using Harness Adaptor (1598/11). See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) .
4. Connect LED Tester (VAG 1527B) between test box terminals No. 11 and 45. Turn ignition on. Turn A/C on as in step 2). If LED comes on, replace PCM. If LED does not come on, check circuit between A/C-heater control panel and PCM. If circuit is okay, replace A/C-heater control panel.

CAMSHAFT POSITION (CMP) SENSOR

1. Disconnect CMP sensor connector. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) . Connect Test Box (VAG 1598) to PCM with Adapter Cable (VAG 1598/11). Connect LED Tester (1115) between test box terminals No. 8 and 46. Operate starter for several seconds.
2. If LED flashes at each second engine revolution, go to next step. If LED does not flash at each second engine revolution, check for faulty wiring. If wiring is okay, go to next step.
3. Turn ignition on. Check voltage between test box terminals No. 7 and 45. If 9 volts minimum is not present, replace PCM. If 9 volts minimum is present, check voltage between test box terminals No. 8 and 45. If 4 volts minimum is not present, replace PCM. If 4 volts minimum is present, replace CMP sensor.

Note. CTP switch is part of TP sensor.

CLOSED THROTTLE POSITION (CTP) SWITCH

1. Ensure throttle cable is adjusted. See THROTTLE CABLE in the «ADJUSTMENTS»(/audi/cabriolet/i-1991-2000/remont/adjustments/#engine-controls-adjustments) article. Remove noise damper. Disconnect Throttle Position (TP) sensor connector. Measure resistance between TP sensor connector terminals No. 4 and 6. (Scheme 9)
2. Resistance should be zero ohms. Open throttle slightly. Resistance should be infinite (open). If resistance is not as specified, adjust closed throttle position (CTP) switch. See CLOSED THROTTLE POSITION (CTP) SWITCH in «ADJUSTMENTS»(/audi/cabriolet/i-1991-2000/remont/adjustments/#engine-controls-adjustments) article. Replace TP sensor if resistance cannot be obtained after adjustment.
3. After adjustment, perform BASIC ENGINE SETTING. Refer to the «TESTS W/CODES»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-tests-wcodes) article. Observe displayed value in channel 2.

CRANKSHAFT POSITION (CKP) SENSOR

Disconnect CKP sensor connector. See ELECTRICAL COMPONENT LOCATIONS. Measure resistance between specified terminals of CKP sensor connector. See CKP SENSOR RESISTANCE table. (Scheme 6) If resistance is not as specified, replace CKP sensor. If resistance is as specified, check wiring between CKP sensor and PCM. If wiring is okay, replace PCM.

CKP SENSOR RESISTANCE

Scheme 7

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

Disconnect ECT sensor connector. See the ELECTRICAL COMPONENT LOCATIONS . Measure resistance between ECT sensor terminals. If resistance is not as specified, replace ECT sensor. See ECT SENSOR RESISTANCE table. If resistance is as specified, check wiring. If wiring is okay, replace PCM.

ECT SENSOR RESISTANCE

ENGINE SPEED (RPM) SENSOR

1. Raise left front wheel off of ground. Read individual measuring values in channel 15. See READ INDIVIDUAL MEASURING VALUES MODE in «TESTS W/CODES»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-tests-wcodes) article. With ignition on, turn left front wheel by hand and observe engine RPM displayed on Scan Tester (VAG 1551).
2. If RPM is displayed, RPM sensor is okay. If RPM is not displayed, check for faulty wiring. If wiring is okay, replace PCM. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) .

HEATED OXYGEN SENSOR (HO2S) HEATING ELEMENT

1. Disconnect HO2S heating element connector. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) . Connect voltmeter between harness connector terminals. Start engine and let idle. If battery voltage is not present, check for faulty circuit breaker, wiring or fuel pump relay.
2. If battery voltage is present, connect Test Cable (VAG 1315 A/1) to HO2S heating element connector. Run engine at idle. Set ammeter on 10-amp scale. Check amperage at test cable terminals. If 0.5-3.0 amps is present, heating element is okay. If 0.5-3.0 amps is not present, replace HO2S.

Note. To check HO2S control function, read individual measuring values in channels 2 and 3. See READING INDIVIDUAL MEASURING VALUES in TESTS W/CODES article.

HEATED OXYGEN SENSOR (HO2S) CONTROL

1. Disconnect HO2S connector. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Measure resistance between engine ground and HO2S connector terminal (component side of connector). If resistance is not infinite, replace HO2S.
2. If resistance is infinite, set voltmeter on 2 volt DC scale. Turn ignition on. Measure voltage between engine ground and HO2S connector terminal (component side of connector). If 350-450 millivolts are present, HO2S is okay. If 350-450 millivolts are not present, check wiring. If wiring is okay, replace PCM.

KICKDOWN SWITCH

Remove noise damper. Disconnect kickdown switch connector. See ELECTRICAL COMPONENT LOCATIONS . Measure resistance between kickdown switch connector terminals. If there is no continuity, kickdown switch is adjusted properly. If there is continuity, adjust kickdown switch. Refer to KICKDOWN SWITCH in the ADJUSTMENTS article. If continuity is still not as specified after adjustment, replace kickdown switch.

MASS AIRFLOW (MAF) SENSOR

1. Ensure circuit breaker is okay. Disconnect MAF sensor connector. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests). Turn ignition on. Measure voltage between MAF sensor connector terminals No. 2 and 3. (Scheme 8) If battery voltage is not present, check for faulty wiring.
2. If battery voltage is present, check wiring between MAF sensor and PCM. If wiring is okay, push back protective boot on MAF sensor connector. Turn ignition on.
3. Measure voltage between MAF sensor connector terminals No. 1 and 2. If 0.3-1.1 volts is not present, replace MAF sensor. If 0.3-1.1 volts is present, start engine.
4. Turn off all electrical accessories. Ensure radiator cooling fan is not running. Vary engine speed between idle and 4000 RPM while measuring voltage between terminals No. 1 and 2. If 1.5-3.4 volts is present, system is okay. If 1.5-3.4 volts is not present, replace MAF sensor.

Scheme 8

Note. TP sensor is automatically adjusted when TP switch is adjusted.

THROTTLE POSITION (TP) SENSOR

1. Disconnect TP sensor connector. Turn ignition on. Measure voltage between TP sensor connector terminals No. 1 and 2, and terminals No. 1 and 3. (Scheme 9) If 4.5-5.5 volts is not present, check for faulty wiring or PCM.
2. If 4.5-5.5 volts is present, measure resistance between TP sensor connector terminals No. 1 and 2 (component side). Resistance should be 1500-2600 ohms. With throttle closed, measure resistance between TP sensor connector terminals No. 2 and 3 (component side). Resistance should be 750-1300 ohms.
3. Slowly open throttle to fully open position. Resistance should increase to 3600 ohms maximum. If resistance is as specified, TP sensor is okay. If resistance is not as specified, replace TP sensor.

Scheme 9

Fuel Pump Relay

See FUEL DELIVERY under FUEL SYSTEM.

EGR Control Solenoid Valve

See EMISSION SYSTEMS & SUB-SYSTEMS .

EVAP Control Solenoid Valve

See EMISSION SYSTEMS & SUB-SYSTEMS .

Fuel Injector Solenoid(s)

See FUEL CONTROL under FUEL SYSTEM.

IAC Valve

See IDLE CONTROL SYSTEM .

FUEL SYSTEM

FUEL PRESSURE RELEASE

Remove fuel pump relay. See ELECTRICAL COMPONENT LOCATIONS . Start engine. Allow engine to run until it stops. Turn ignition off. Disconnect negative battery cable. Slight pressure may remain in system. Before disconnecting any fuel system line, cover connector with a clean shop towel. Install fuel pump relay.

Fuel Injectors

1. Disconnect fuel injector connector. Measure resistance across fuel injector connector terminals. If resistance is not 15-17 ohms, replace fuel injector. If resistance is 15-17 ohms, connect LED Tester (US 1115) between engine ground and fuel injector connector terminal No. 2. (Scheme 10)
2. Operate starter for several seconds. If LED comes on, go to next step. If LED does not come on, check fuel pump relay, circuit breaker and wiring. See «FUEL DELIVERY»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests__fuel-delivery). If fuel pump relay, circuit breaker and wiring are okay, connect LED tester between battery positive source and fuel injector connector terminal No. 1.
3. Operate starter for several seconds (engine may start). If LED flashes, fuel injector system is okay. If LED does not flash, check for faulty wiring. If wiring is okay, replace PCM. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests).

Scheme 10

Fuel Injector Leakage & Volume

1. Ensure fuel system pressure is okay. See «BASIC TESTING»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-basic-testing) article. Remove intake air hose between mass airflow sensor and noise damper. Disconnect and move spark plug wires aside to allow fuel rail to be removed.
2. Disconnect fuel injector connectors. Disconnect vacuum hose from fuel pressure regulator. Remove fuel rail from manifold with injectors attached to fuel rail. Suspend fuel rail with wire. In Output DTM, activate fuel pump relay. See OUTPUT DIAGNOSTIC TEST MODE (DTM) under SELF-DIAGNOSTIC TESTS in «TESTS W/CODES»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-tests-wcodes) article. If more than 2 drops of fuel per minute falls from fuel injector, replace fuel injector and "O" ring.
3. If less than 2 drops of fuel per minute falls from fuel injector, set a clear measuring container under fuel injector to be tested. Connect jumper wire between engine ground and one terminal of fuel injector. For 30 seconds, connect jumper wire between battery positive source and other terminal of fuel injector connector.
4. If output is 85-100 milliliters, volume is okay. If output is not 85-100 milliliters, replace fuel injector.

FUEL DELIVERY

Note. Fuel pump connector is accessible through trunk floor.

Fuel Pump Circuit Without Scan Tester

1. Ensure fuse No. 13 is okay. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests). Ensure fuel filter is okay and battery is fully charged. While operating starter for several seconds, measure voltage at fuse No. 13.
2. If battery voltage is not present, go to next step. If battery voltage is present, check for open circuit between fuse No. 13 and fuel pump, and between fuel pump and ground. If circuit is okay, replace fuel pump.
3. Check fuel pump relay. See FUEL PUMP RELAY - WITHOUT SCAN TESTER. If fuel pump relay is okay, remove it. Turn ignition on. Check voltage at fuel pump relay terminals No. 46 and 48. (Scheme 11) If battery voltage is not present, repair relay power supply circuit.
4. If battery voltage is present, check for open circuit between fuel pump relay connector terminal No. 52 and fuse No. 13. If circuit is okay, check for open circuit between fuel pump relay connector terminal No. 47 and PCM. If circuit is okay, replace PCM.

Fuel Pump Relay Without Scan Tester

Remove fuel pump relay. Refer to the ELECTRICAL COMPONENT LOCATIONS. Without voltage applied to relay, there should be no continuity between terminals No. 48 and 52, and between terminals No. 48 and 59. (Scheme 11) With battery voltage applied across terminals No. 28 and 29, there should be continuity between terminals No. 48 and 52, and between terminals No. 48 and 59. If continuity is not as specified, replace relay.

Fuel Pump Relay Using Scan Tester

1. Remove fuse No. 13. Refer to the «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests). Using jumper wire from Adaptor Kit (VW 1594), connect LED Tester (VAG 1527B) between chassis ground and rear terminal of fuse No. 13 receptacle.
2. Initiate OUTPUT DTM. See «TESTS W/CODES»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-tests-wcodes) article. In output DTM, activate fuel pump relay. Fuel pump relay should click and LED should come on. If fuel pump relay does not click, go to step 6). If fuel pump relay clicks but LED does not come on, remove fuel pump relay. Check for faulty wiring between fuse No. 13 and terminal No. 52 of fuel pump relay connector. (Scheme 11)
3. If wiring is okay, install fuel pump relay and fuse No. 13. Remove fuse No. 28. Connect LED tester between chassis ground and either terminal of fuse No. 28 receptacle.
4. In output DTM, activate fuel pump relay. Fuel pump relay should click and LED should come on. If fuel pump relay does not click, go to step 6). If fuel pump relay clicks but LED does not come on, connect LED tester between chassis ground and other terminal of fuse No. 28 receptacle.
5. In output DTM, activate fuel pump relay. If LED still does not come on, remove fuel pump relay. Check wiring between fuse No. 28 and terminal No. 59 of fuel pump relay connector. If wiring is faulty, repair or replace wiring as necessary. If wiring is okay, replace fuel pump relay.
6. Turn ignition off. Remove fuel pump relay. Turn ignition on. Check voltage between relay connector terminals No. 46 and 50, and terminals No. 48 and 50. (Scheme 11)
7. If battery voltage is not present across both sets of terminals, repair wiring. If battery voltage is present across both sets of terminals, connect LED tester between terminals No. 46 and 47. When ignition is turned on, LED should come on brightly for about one second, then become dim and stay dim. When starter is engaged, LED should become distinctly brighter.
8. If LED comes on, replace fuel pump relay. If LED does not come on, use Adaptor Cable (1598/12) to connect Test Box (VAG 1598) to Electronic Control Module (PCM) wiring harness connector. Leave PCM disconnected.
9. Measure resistance between relay connector terminal No. 47 and test box terminal No. 15. If resistance is more than one ohm, repair wiring as necessary. If resistance is less than one ohm, replace PCM.

Scheme 11

FUEL PRESSURE

Note. If fuel comes out of fuel pressure regulator vacuum port when hose is disconnected, replace fuel pressure regulator.

System Pressure

1. Ensure fuse No. 13 (fuse No. 17 on A6 model) is okay, fuel filter is in good condition and battery voltage is 12 volts minimum. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) . Connect Pressure Gauge (VAG 1318) between fuel supply line and fuel rail. Open pressure gauge lever. Disconnect vacuum hose from fuel pressure regulator. Plug open end of vacuum hose.
2. Initiate OUTPUT DTM. See «TESTS W/CODES»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-tests-wcodes) article. Activate fuel pump relay. If fuel pump does not operate, check fuel pump. See «FUEL DELIVERY»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests__fuel-delivery) . If fuel pump operates, check fuel pressure. If fuel pressure is 55-61 psi (3.8-4.2 kg/cm 2 ), go to step 4).
3. If fuel pressure is not as specified, replace fuel pressure regulator and recheck pressure. If fuel pressure is less than specified, check for damaged fuel pump or restricted fuel supply line. If fuel pressure exceeds specification, check for restricted fuel return line. WARNING: Excessive fuel pressure may rupture fuel pressure regulator diaphragm, causing fuel to enter engine through vacuum hose. This could result in an explosion. NOTE: When vacuum hose is disconnected from fuel pressure regulator, mixture is enriched. DO NOT operate engine for longer than necessary with hose disconnected, as oxygen sensor limits may be exceeded, causing a code to set.
4. Turn off all electrical accessories. Run engine at idle (this automatically interrupts output DTM). Ensure radiator cooling fan is not running.
5. Difference in fuel pressure with vacuum hose connected and disconnected at fuel pressure regulator should be about 7.3 psi (0.5 kg/cm 2 ). If difference is as specified, system is okay. If difference is not as specified, check for faulty vacuum hose or blocked vacuum port at intake manifold. Repair or replace as necessary. If hose and vacuum port are okay, replace fuel pressure regulator.

Residual Pressure

1. Connect Pressure Gauge (VAG 1318) between fuel supply line and fuel rail. Open pressure gauge lever. Start engine. Turn off engine. Wait 10 minutes. Residual pressure should be 44 psi (3.1 kg/cm 2 ). After 20 minutes, residual pressure should be 32 psi (2.2 kg/cm 2 ).
2. If system fuel pressure is low, check fuel pump check valve, sensor plate free play, fuel distributor "O" rings and seats. Replace if necessary. If these components are okay, replace fuel pressure regulator.

IDLE AIR CONTROL (IAC) VALVE

1. Disconnect electrical connector from Idle Air Control (IAC) valve. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) . Measure resistance between IAC valve connector terminals. If resistance is not 7-11 ohms, replace IAC valve. If resistance is 7-11 ohms, remove IAC valve.
2. Looking through hole in IAC valve, check for scored rotary slide valve. Replace IAC valve if rotary slide valve is scored. If rotary slide valve is okay, reconnect IAC valve connector. Turn ignition on. Initiate Output DTM. See OUTPUT DIAGNOSTIC TEST MODE (DTM) under SELF-DIAGNOSTIC TESTS in «TESTS W/CODES»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-tests-wcodes) article. Observe rotary slide valve when IAC valve is activated during Output DTM.
3. If rotary slide valve travels freely from stop to stop, system is okay. If rotary slide valve shows signs of movement but does not travel freely from stop to stop, replace IAC valve. If rotary slide valve is not activated during Output DTM, check wiring. If wiring is okay, replace PCM.

IGNITION COIL PRIMARY RESISTANCE

Disconnect ignition coil 3-pin connector. See ELECTRICAL COMPONENT LOCATIONS. Disconnect power output stage 3-pin connector. Measure resistance between matching terminals of each connector (terminals No. 1 and 1, 2 and 2, and 3 and 3). (Scheme 12) If resistance is not 0.5-1.0 ohm, replace appropriate coil.

Scheme 12

IGNITION COIL PRIMARY VOLTAGE SUPPLY

Turn ignition on. Disconnect ignition coil 3-pin connector. See ELECTRICAL COMPONENT LOCATIONS. Connect LED Tester (VAG 1527B) between engine ground and each terminal of ignition coil 3-pin connector, in sequence. (Scheme 12) If LED comes on when terminals are probed, voltage supply is okay. If LED does not come on, check fuse No. 32 and wiring. Repair or replace as necessary.

IGNITION COIL SECONDARY RESISTANCE

Disconnect spark plug wires from ignition coil being tested. Measure resistance between coil towers of ignition coil being tested. If resistance is 9000-14,000 ohms, coil secondary circuit is okay. If resistance is not 9000-14,000 ohms, replace coil.

POWER OUTPUT STAGE

1. Disconnect power output stage 4-pin connector. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) . Connect LED Tester (1527B) between vehicle battery positive source and Brown/Red wire (ground) terminal of power output stage 4-pin connector. If LED does not come on, repair Brown/Red wire.
2. If LED comes on, disconnect all fuel injector electrical connectors. Turn ignition on. Connect LED tester between engine ground and remaining 3 terminals of power output stage 4-pin connector, in sequence. Operate starter for several seconds while probing each terminal.
3. If LED comes on, replace ignition coil power output stage. If LED does not come on, check wiring between PCM and power output stage. If wiring is okay, replace PCM.

1. Disconnect harness connector from EGR control solenoid valve. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests). Measure resistance across EGR control solenoid valve terminals. (Scheme 10) If resistance is not 25-35 ohms, replace EGR control solenoid valve.
2. If resistance is 25-35 ohms, connect LED Tester (US 1115) between engine ground and EGR control solenoid valve connector terminal No. 1 with jumper from Adaptor Kit (VW 1594). Operate starter for several seconds. If LED does not come on, check circuit breaker, wiring and fuel pump relay.
3. If LED comes on, connect LED tester between EGR control solenoid valve connector terminals with jumper from adaptor kit. In self-diagnostics mode, initiate Output Diagnostic Test Mode (Output DTM). LED tester should flash when Output DTM is initiated for EGR control solenoid valve.
4. If LED flashes as specified, system is okay. If LED does not flash as specified, check wiring harness. If wiring harness is okay, replace PCM.

EGR Temperature (EGRT) Sensor

1. Disconnect EGRT sensor connector. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) . Turn ignition on. Measure voltage between EGRT sensor connector terminals. If 4.5-5.0 volts is not present, repair faulty wiring or replace PCM as necessary.
2. If 4.5-5.0 volts is present, turn ignition off. Remove EGRT sensor. Set ohmmeter to 200,000-ohm scale. Place EGRT sensor in boiling water. Measure resistance across EGRT sensor terminals. If resistance changes, EGRT sensor is okay. If resistance does not change, replace EGRT sensor.

1. Disconnect EVAP control solenoid valve connector. See «ELECTRICAL COMPONENT LOCATIONS»(/audi/cabriolet/i-1991-2000/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Measure resistance across EVAP control solenoid valve terminals. (Scheme 10) If resistance is not 20-28 ohms, replace EVAP control solenoid valve.
2. If resistance is 20-28 ohms, connect LED Tester (US 1115) between engine ground and EVAP control solenoid valve connector terminal No. 1 with jumper from Adaptor Kit (VW 1594). Operate starter for several seconds. If LED does not come on, check circuit breaker, wiring and fuel pump relay.
3. If LED comes on, connect LED tester between EVAP control solenoid valve connector terminals with jumper from adaptor kit. Initiate Output DTM. LED tester should flash when Output DTM is initiated for EVAP control solenoid valve.
4. If LED flashes as specified, system is okay. If LED does not flash as specified, check wiring harness. If wiring harness is okay, replace PCM.

TIMING CONTROL SYSTEMS

Note. Ignition timing is electronically controlled by PCM. Information is not available from manufacturer.

THROTTLE CONTROLS

Note. Information is not available from manufacturer.

See also:
• TESTS W/CODES
• ADJUSTMENTS
• BASIC TESTING
• ELECTRICAL COMPONENT LOCATIONS
• FUEL DELIVERY