Checking components and wiring
Check the resistance of the engine coolant temperature sensor. For the resistance values, see Components resistance values .
Check the cable between control module terminal #16 and the signal terminal for the engine coolant temperature (ECT) sensor. Check for a short-circuit to ground. See Short-circuit to ground, permanent faults .
HINT: It is difficult to separate the ground lead for the engine coolant temperature sensor from the signal cable. Therefore, measure one cable at a time and see if the permitted values are present on either of them.
Remedy as necessary.
Other information:
- To access the control module or connect the breakout box, see Connecting the breakout box
- To access or replace the engine coolant temperature sensor:
- For cars manufactured up to w38 2001 inclusive, see Overheat protection thermostat / flame sensor / engine coolant temperature sensor, replacing
- For cars manufactured from w39 2001 inclusive, see Replacing the overheat protection thermostat, the flame sensor and the engine coolant temperature sensor .
- With the ignition on and the signal cable for the engine coolant temperature sensor cut, the voltage between the signal cable for the engine coolant temperature sensor (engine control module (ECM) side) and ground should be approximately 5 V
- For other values, see Signal specification .
- Continue
Refer to Verification