Symptom Related Diagnostic Procedures
Warning Light Flashing Low Oil Level In Reservoir1. Air trapped in hydraulic system has escaped during driving. Top up oil in reservoir to ``MAX'' mark.
2. Leaks in steering gear, at pipe unions or at pump. Tighten pipe unions, replace O-rings, seal in pump or pipes/hoses.
3. Seal in valve housing leaking on steering column side. Replace seal and O-ring
Warning Light Flashing Again, Low Oil Level In Reservoir, No Visible Leaks
1. Leaking steering rack. Install rebuilt steering gear.
2. Seal in lefthand end housing leaking. Install rebuilt steering gear.
Warning Light Flashing, Oil Level In Reservoir Satisfactory
1. Oil sieve in reservoir plugged. Clean sieve, and if necessary, replace reservoir.
2. Float for warning light defective. Replace reservoir cap.
3. Pressure switch on brake servo defective. Replace pressure switch, if necessary.
Warning Light Flashes After Engine Started, Then Goes Out
1. Brake servo leaking. Replace brake servo, if necessary.
2. Check valve in accumulator leaking. Replace check valve, if necessary.
Reservoir Fluid Runs Over
1. Seals in hydraulic pump leaking. Repair or replace hydraulic pump.
Steering Heavy
1. V-belt loose. Tighten belt, replace if necessary.
2. Pump pressure too low. Check pump pressure.
Steering Makes A Rattling Or Knocking Noise
1. Excessive play between pressure plate and steering rack. Adjust Steering gear.
Noise At Idle Or Steering Wheel Vibrates When Stopped
1. V-belt defective or tension incorrect. Tighten belt, replace if necessary.
2. Hydraulic pump defective. Replace hydraulic pump.
Servotronic System
Refer to SCHEMATIC DIAGRAMS/ELECTRICAL AND ELECTRONIC DIAGRAMS when troubleshooting.
Steering Difficult When Vehicle Stationary, Engine Idling Or During Slow Driving
1. No voltage supply at Servotronic control unit. Check voltage supply.
2. Wiring from Servotronic control unit to Servotronic valve defective. Check wiring.
3. Electrical fault in Servotronic valve. Check Servotronic valve.
4. Servotronic control unit defective. Replace Servotronic control unit as a test. If fault is not eliminated, install original control unit.
5. Hydraulic defect in steering system. Check pump pressure, if satisfactory, replace steering gear. If not, replace pump.
Steering Effort Too Light At Higher Speeds
1. Servotronic control unit defective. Replace Servotronic control unit as a test. If fault is not eliminated, install original control unit.
2. No speed signal at Servotronic control unit. Check wiring and connection. Speed signal can also be suppressed or falsified by faults in other systems.
3. Oil strainer or port in Servotronic valve blocked. Clean strainer, then replace Servotronic valve, if necessary.
Steering Effort Too Heavy Intermittently
1. Servotronic valve wiring has short to ground. Check wiring and connections to valve.
Steering Effort Too Light Intermittently
1. Servotronic valve wiring is shorted. Check wiring and connections to valve.
Steering Satisfactory While Idling When Vehicle Stationary, But Too Heavy When Driving
1. Servotronic control unit defective. Replace Servotronic control unit as a test. If fault is not eliminated, install original control unit.
2. Hydraulic defect in steering system. Replace steering gear.
Steering Effort Unequal For Left & Right Turns
1. Hydraulic defect in steering system. Replace steering gear.
Fig. 2 Servotronic Control Unit Electrical Connector Pin Identification. V8 Quattro:
Voltage Supply, Checking
1. Remove shelf and kneebar on drivers side, then remove Servotronic control unit.
2. Disconnect electrical connector from Servotronic control unit, then turn ignition switch to On position.
3. Connect multimeter US 1119 or equivalent set to 20 V range, between terminals 2 and 7, and 3 and 7 on Servotronic control unit connector, Fig. 2.
4. If reading is not approximately 12 V, check for open circuit in wiring and repair as necessary.
Wiring Between Servotronic Control Unit & Servotronic Valve, Checking
1. Remove shelf and kneebar on drivers side, then remove Servotronic control unit.
2. Disconnect electrical connector from Servotronic control unit, then remove air duct.
3. Disconnect electrical connector from Servotronic valve, then connect multimeter US 1119 or equivalent between terminals 8 and 11 on Servotronic control unit connector, Fig. 2.
4. If reading is not infinite ohms, check for short circuit in wiring and repair as necessary.
5. If reading is infinite ohms, leave multimeter connected and bridge terminals on electrical connector for Servotronic valve.
6. If reading is not approximately 0 ohms, check for open circuit in wiring and repair as necessary.
Servotronic Valve, Checking
1. Remove shelf and kneebar on drivers side, then remove Servotronic control unit.
2. Disconnect electrical connector from Servotronic control unit, then connect multimeter US 1119 or equivalent set to ohm range, between terminals 8 and 11 on Servotronic control unit connector, Fig. 2.
3. If reading is not 6-12 ohms, remove steering gear and replace Servotronic valve.
Electrical Connection To Servotronic Valve, Checking For Short To Ground
1. Remove shelf and kneebar on drivers side, then remove Servotronic control unit.
2. Disconnect electrical connector from Servotronic control unit, then connect multimeter US 1119 or equivalent set to ohm range, between terminals 2 and 11, 3 and 11, 2 and 8 and 3 and 8 on Servotronic control unit connector, Fig. 2.
3. If reading is not infinite ohms, check for short circuit in wiring and repair as necessary.
Electrical Connection To Servotronic Valve, Checking For Short
1. Remove shelf and kneebar on drivers side, then remove Servotronic control unit.
2. Disconnect electrical connector from Servotronic control unit, then connect multimeter US 1119 or equivalent set to ohm range, between terminals 7 and 8 and 7 and 11 on Servotronic control unit connector, Fig. 2.
3. If reading is not infinite ohms, check for short circuit in wiring and repair as necessary.