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.
1991 Audi 100 BaseFACTORY OEM SERVICE PROCEDURE
Control Units
CONTROL UNITS LOCATION
| Component | Location |
|---|---|
| A/C Blower Control Unit | On right side of A/C evaporator housing. |
| A/C Control Unit | In center of dash. |
| A/C Climate Control Programmer | Behind glove box. See Figure . |
| ABS Control Unit | Under left rear passenger's seat. |
| Alarm System Control Unit | Under right side of dash. See Figure . |
| Automatic Seat Control Unit | Under driver's seat. |
| Automatic Shift Lock Control Unit (100) | On auxiliary relay panel. See Figure . |
| Cruise Control Unit | Under right side of dash. See Figure . |
| Engine Control Unit (200) | Behind right kick panel. See Figure . |
| Fuel Injection Control Unit (100) | Behind right kick panel. See Figure . |
| Idle Stabilizer & Fuel Deceleration Control Unit (200) | Behind left kick panel. See Figure . |
| Ignition Control Unit (100) | Behind left kick panel. See Figure . |
| Interior Light Delay Control Unit | On auxiliary relay panel. See Figure . |
| Light Control Unit (Front) | On auxiliary relay panel. See Figure . |
| Power Window/Sun Roof Control Units (2) | On auxiliary relay panel. See Figure . |
| Rear Differential Lock Control Unit | Under center of rear seat. |
| Seat Belt Warning Control Unit | On auxiliary relay panel. See Figure . |
| Taillight Control Unit | On left side of trunk, near antenna. |
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.