Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1990 Audi 200 Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Deceleration Fuel Shutoff
- Ensure engine is at normal operating temperature and no fault codes are stored in ECU memory. Using a digital voltmeter and Adapter (VW 1315A/1), check voltage at differential pressure regulator.
- Connect voltmeter to differential pressure regulator using adapter. See Figure . Turn ignition on. Control voltage must be positive (+). If voltage is negative (-), reverse test leads.
- Start engine. Raise engine speed to 3000 RPM and release throttle. Control voltage should switch to negative (-) momentarily. If system fails test, perform electrical tests. See Figure and the CIS-MOTRONIC VOLTAGE & RESISTANCE TESTS table. If system electrical tests are okay, replace ECU and clear fault codes.
CIS-MOTRONIC VOLTAGE & RESISTANCE TESTS
| Test Step | Terminals | Test Conditions | Test Values | ||||
|---|---|---|---|---|---|---|---|
| No. 1 | 14 & 35 | Ignition ON | About Battery Voltage | ||||
| No. 2 | 17 & 35 | Ignition ON | About Battery Voltage | ||||
| No. 3 | 32 & 35 | Ignition & A/C ON | About Battery Voltage | ||||
| No. 4 | 33 & 35 | Ignition & A/C ON | Battery Volts Minus 1 | ||||
| No. 5 | 19 & 35 | Ignition ON | About Battery Voltage | ||||
| No. 6 (1) | 13 & 35 | Insert Fuel | Fault Indicator | ||||
| " | " | Relay Fuse | Must Light | ||||
| " | " | Ignition ON | Fault Indicator Must Light | ||||
| No. 7 | 4 & 5 | Ignition OFF | 15-25 Ohms | ||||
| No. 8 | 3 & 35 | Ignition OFF | 2500 Ohms @ 68°F (20°C) | ||||
| " | " | " | 200 Ohms @ 212°F (100°C) | ||||
| No. 9 | 31 & 35 | Throttle Closed | Open (No Continuity) | ||||
| " | " | Throttle Wide Open | Continuity | ||||
| No. 10 | 28 & 35 | Throttle Closed & Open | Continuity | ||||
| No. 11 (2) | 18 & 35 | " | Continuity | ||||
| No. 12 | 13 & 35 | Insert Fuel Relay Fuse | Continuity | ||||
| " | 13 & 35 | Ground Test Connector | Continuity | ||||
| No. 13 | 14 & 16 | Cold Start Valve Test | About 10 Ohms | ||||
| No. 14 | 14 & 15 | Charcoal Canister Valve Test | 30-60 Ohms | ||||
| No. 15 | " | Unplug Hall Effect Sensor Connector | " | ||||
| " | 30 & 35 | Terminals 1 & 2 To Sensor | Continuity | ||||
| " | 30 & 21 | Terminals 2 & 3 To Sensor | Continuity | ||||
| No. 16 | 11 & 35 | Remove Terminal @ Power Output Stage | " | ||||
| " | " | Of Coil. Ground Center Contact | Continuity | ||||
| No. 17 | " | Disconnect Knock Sensor Connector | Open | ||||
| " | 6 & 8 | Connect Terminals 1 & 2 | Continuity | ||||
| " | " | Connect Terminals 1 & 3 | Continuity | ||||
| No. 18 | 7 & 35 | Disconnect O2 Connector & Gnd | Continuity | ||||
| No. 19 | 23 & 26 | Sensor Plate @ Rest | About 5000 Ohms | ||||
| No. 20 | 26 & 35 | Sensor Plate @ Rest | About 4000 Ohms | ||||
| No. 21 | 34 & 35 | Man. Trans. | Continuity | ||||
| " | " | Auto. Trans. In "P" Or "N" | Open | ||||
| No. 22 | 12 & 35 | Remove Fuel Pump Relay & Ground | " | ||||
| " | " | Pin 47 Of Fuse Panel Relay | Continuity | ||||
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Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.