Checking components and wiring
- Check the resistance of the engine coolant temperature sensor
- Check the cable between combustion preheater module (CPM) terminal #4 and the ground terminal for the engine coolant temperature sensor. Check for a short-circuit to ground.
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 plausible values are obtained from either of them.
Remedy as necessary.
Other information
- See Connecting the breakout box
- See Signal specification
- For resistance values: Components resistance values
- 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 .
- See Contents
- Continue
Refer to Verification
- Check the combustion preheater module (CPM) connectors. Check for contact resistance and oxidation
- Check the cable between combustion preheater module (CPM) terminal #16 and the signal terminal for the engine coolant temperature sensor. Check for an intermittent short-circuit to ground.
Remedy as necessary.
Other information
- See Connecting the breakout box
- See Signal specification
- For resistance values See Components resistance values
- 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 .
- See Contents
- Continue
Refer to Verification