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.
1986 Mercedes Benz 560SECFACTORY OEM SERVICE PROCEDURE
Testing Coolant Temperature Sensor
- Unplug coolant temperature sensor. Test resistance from sensor terminal to ground (idle speed okay with connection to ground or too high with interruption). For nominal value see Fig 1 . If not okay, replace coolant temperature sensor. If okay, go to step 2).
- Check wire (Green/Red) between terminal No. 21 of CIS-E control unit plug to plug of coolant temperature sensor for continuity. Resistance should be about zero ohms. If not okay, repair interruption. If okay, test is complete.
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.