ELECTRICAL COMPONENT LOCATOR 1991 AUDI ELECTRICAL COMPONENTS

Audi 90 Quattro 1991 - BUZZERS, RELAYS & TIMERS

Audi 90 Quattro 1991 BUZZERS, RELAYS & TIMERS LOCATION

Component	Location
A/C Clutch Control Relay	On auxiliary relay panel, position No. 4. See Fig. 1 .
A/C-Heater Blower Motor Relay	On main fuse/relay panel, position No. 6. See Fig. 2 .
A/T Inhibitor Relay	On main fuse/relay panel, position No. 8. See Fig. 2 .
ABS System
Return Pump Relay	On ABS hydraulic control unit (large relay).
Solenoid Valve Relay	On ABS hydraulic control unit (small relay). See Fig. 1 .
System Relay	On auxiliary relay panel, position No. 1. See Fig. 1 .
Control Unit Relay	On auxiliary relay panel, position No. 16. See Fig. 1 .
Driver's Seat Heater Control Relay	On auxiliary relay panel, position No. 14. See Fig. 1 .
Fog Light Relay	On main fuse/relay panel, position No. 1. See Fig. 2 .
Front Light Control Unit Relay	On auxiliary relay panel, position No. 6. See Fig. 1 .
Fuel Pump Relay	On main fuse/relay panel, position No. 10. See Fig. 2 .
Horn Relay	On main fuse/relay panel, position No. 7. See Fig. 2 .
Interior Light Control Relay	On auxiliary relay panel, position No. 3. See Fig. 1 .
Intermittent Wiper Relay	On main fuse/relay panel, position No. 9. See Fig. 2 .
Load Reduction Circuit Relay	On main fuse/relay panel, position No. 5. See Fig. 2 .
Passenger Seat Heater Control Relay	On auxiliary relay panel, position No. 13. See Fig. 1 .
Power Window & Sun Roof Relay	On auxiliary relay panel, position No. 15. See Fig. 1 .
Radiator Cooling Fan
After-Run Fan Relay	On auxiliary relay panel, position No. 18. See Fig. 1 .
Low-Speed Relay	On main fuse/relay panel, position No. 11. See Fig. 2 .
High-Speed Relay	On main fuse/relay panel, position No. 2. See Fig. 2 .
Seat Belt Warning Relay	On auxiliary relay panel, position No. 2. See Fig. 1 .
Turn Signal/Hazard Flasher	Under dash, left of steering column. See Fig. 3 .
Upshift Relay	On main fuse/relay panel, position No. 3. See Fig. 2 .

Audi 90 Quattro 1991 - CIRCUIT PROTECTION DEVICES

Audi 90 Quattro 1991 CIRCUIT PROTECTION DEVICES LOCATION

Component	Location
Auxiliary Relay Panel	Under left side of dash. See Fig. 3 .
Circuit Breaker: Power Seats & Memory Mirrors	On auxiliary relay panel, position No. 12. See Fig. 1 .
Main Fuse/Relay Panel	On left side of engine compartment.

Audi 90 Quattro 1991 - CONTROL UNITS

Audi 90 Quattro 1991 CONTROL UNITS LOCATION

Component	Location
ABS Control Unit	Under left side of rear seat.
Board Computer (Auto-Check Module)	On back of instrument cluster. See Fig. 3 .
Cruise Control Unit	Behind right side of dash, above glove box. See Fig. 3 .
Differential Lock Control Unit	Under right side of rear seat.
Fuel Injection Control Unit	Behind A/C evaporator. See Fig. 3 .
Ignition Electronic Control Unit	Behind right kick panel. See Fig. 3 .
Power Seat Memory Control Unit	Under driver's seat. See Fig. 3 .
Rear Light Control Units
Input Control (White Connector)	On left side of trunk, behind access panel.
Output Control (Black Connector)	On left side of trunk, behind access panel.

Audi 90 Quattro 1991 - SENDING UNITS & SENSORS

Audi 90 Quattro 1991 SENDING UNITS & SENSORS LOCATION

Component	Location
A/C Outside Air Temperature Sensor	In A/C-heater fresh air inlet.
ABS Wheel Speed Sensors	At each wheel.
Airflow Sensor (Potentiometer)	On fuel distribution head. See Fig. 4 .
Altitude Sensor	Behind right front kick panel. See Fig. 3 .
Coolant Temperature Sending Unit	At front of cylinder head.
Cruise Control Speed Sensor	On back of speedometer.
Dual Temperature Sensor	On coolant flange housing.
Fuel Gauge Sending Unit	On top right side of fuel tank (accessible from trunk).
Knock Sensor	On left side of engine block. See Fig. 4 .
Oxygen Sensor	In exhaust manifold. See Fig. 4 .
Vehicle Speed Sensor	On left side of transmission, near drive axle flange.

Audi 90 Quattro 1991 - MOTORS

Audi 90 Quattro 1991 MOTORS LOCATION

Component	Location
A/C-Heater Blower Motor	Under right side of dash.
ABS Hydraulic Control Motor	On left rear of engine compartment. See Fig. 4 .
Central Lock System Motor	On right side of trunk, behind access panel.
Electric Fuel Pump	Under vehicle.
Front Wiper Motor	On firewall.
Power Door Lock Motor	In trunk, on right wheelwell.
Radiator Cooling Fan	On left side of radiator. See Fig. 4 .
Windshield Washer Motor	In washer reservoir.
Windshield Wiper Motor	On firewall, in engine compartment. See Fig. 4 .

Audi 90 Quattro 1991 - SOLENOIDS & SOLENOID VALVES

Audi 90 Quattro 1991 SOLENOIDS & SOLENOID VALVES LOCATION

Component	Location
Carbon Canister Frequency Valve	In canister purge hose, next to canister. See Fig. 4 .
Carbon Canister On/Off Valve	In canister purge hose, next to frequency valve. See Fig. 4 .
Cold Start Valve	In rear of intake manifold. See Fig. 4 .
Cruise Control Vacuum Vent Valves	On brake & clutch pedal.
Idle Stabilizer Valve	In air by-pass hose. See Fig. 4 .
Power Door Lock Control Solenoid	In left front door.

Audi 90 Quattro 1991 - SWITCHES

Audi 90 Quattro 1991 SWITCHES LOCATION

Component	Location
A/C High Pressure Cut-Out Switch	On A/C liquid line, near condenser (red housing).
A/C Microswitch	On side of A/C-heater control panel.
A/C Refrigerant High Pressure Switch	On A/C liquid line, near condenser (yellow/green housing).
A/C Refrigerant Low Pressure Switch	On right side of engine compartment, near evaporator housing.
A/C Temperature Switch	On rear of A/C-heater control panel.
ABS Hydraulic Pressure Switch	On ABS Hydraulic Control Unit.
Auto-Check System Thermoswitch	On coolant hose housing at cylinder head (2-wire).
Auto-Check System Electronic Thermoswitch (4-Wire)	On coolant hose housing, at cylinder head.
Back-Up Light Switch (M/T)	On rear of transmission housing.
Back-Up/Neutral Start Switch (A/T)	On bracket, under A/T gearshift selector console.
Brake Fluid Level Warning Switch	In bottom of brake fluid reservoir. See Fig. 4 .
Brake/Stoplight Switch	On pedal bracket, at top of brake pedal.
Cold Start Thermoswitch	In rear of cylinder head.
Coolant Level Warning Switch	In bottom of coolant reservoir.
Engine Coolant Temperature Switch (Non-A/C)	On thermostat housing, at cylinder head. See Fig. 4 .
Idle Switch	On throttle linkage. See Fig. 4 .
Oil Pressure Switch	In engine block, ahead of oil dipstick.
Parking Brake Switch	At base of parking brake lever.
Radiator Cooling Fan
After-Run Switch	In front of intake manifold. See Fig. 4 .
Thermoswitch	In lower left side of radiator. See Fig. 4 .
Seat Belt Switch	In driver's seat belt buckle.
Thermo Time Switch	At rear of cylinder head, below distributor.
Wide Open Throttle (WOT) Switch	On throttle linkage. See Fig. 4 .

Audi 90 Quattro 1991 - MISCELLANEOUS

Audi 90 Quattro 1991 MISCELLANEOUS LOCATION

Component	Location
Antenna Amplifier (Windshield)	In right side windshield pillar. See Fig. 3 .
Antenna Amplifier (Rear Window)	In trunk, below trunk latch.
Blower Motor Ballast Resistor	On blower housing.
Center Console Light Booster	Under dash, on right side of steering column. See Fig. 3 .
Diagnostic Connector	In fuse socket, on fuel pump relay.
Ignition Amplifier	On ignition coil bracket. See Fig. 4 .
Ignition Coil	At center of firewall. See Fig. 4 .
Instrument Panel Voltage Regulator	On right rear of instrument panel.
Radiator Cooling Fan Resistor	Behind left side of grille. See Fig. 4 .