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 BMW 535iFACTORY OEM SERVICE PROCEDURE
Control Units
CONTROL UNITS LOCATION
| Component | Location |
|---|---|
| Anti-Lock Brake Control Unit | Behind right shock tower module closest to shock tower). |
| A/C Compressor Control Unit | Behind left kick panel. |
| Check Control Module | On fuse/relay block, in engine compartment. See Figure. |
| Chime Module | Under left side of dash (round unit with 3-pin & 4-pin connectors). |
| Crash Control Unit | On fuse/relay block, in engine compartment. See Figure. |
| Cruise Control Unit | Behind right shock tower second module (forward of firewall). |
| Defogger Control Unit | Behind right center of dash, on right side of A/C-Heater plenum. |
| Electronic Transmission Control Unit (A/T) | Behind right kick panel. |
| Final Stage Unit | Behind right center of dash, on right side of A/C-heater plenum. |
| General Module | Under left side of rear seat, in rear fuse/rear block. See Figure. |
| Integrated Climate Regulation Control Unit | Behind left center of dash, on left side of A/C-heater plenum. |
| Light Control Module | On fuse/relay block, in engine compartment. See Figure. |
| Motronic Control Unit (ECU) | Behind right shock tower (module closest to firewall). |
| On-Board Computer Module | At center of dash, to right of radio. |
| Relay Module | Under left rear seat, in rear fuse/relay block. See Figure. |
| SRS Diagnostic Module (Air Bag) | Behind left side of dash, to left of steering column. |
Factory Service Tools
Use the Manual With the Right Hardware
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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.