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.
1988 BMW 535i AutomaticFACTORY OEM SERVICE PROCEDURE
Test 12: THERMOTIMER
- Check that timer is properly installed and firmly seated. Check radiator for correct coolant level. Bleed cooling system.
- Disconnect timer and check resistance values between plug terminals "G" and "W", "G" and ground, and "W" and ground. If values are correct, trace timer circuit and repair wiring. If values are incorrect, replace timer. See THERMOTIMER RESISTANCE table.
THERMOTIMER RESISTANCE
| Circuit Tested | Resistance | |
|---|---|---|
| "G" to Ground | 40-70 Ohms | |
| "G" to "W" & "W" to Ground | ||
| Above 60°F (15°C) | Infinite | |
| Below 60°F (15°C) | Zero | |
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.