Checking components and wiring
Check the fuel pump (FP) and combustion preheater module (CPM) connectors. Check for contact resistance and oxidation.
Check the cable between combustion preheater module (CPM) terminal #13 and fuel pump (FP) terminal 2. Check for an intermittent open-circuit. Check for an intermittent short-circuit to ground.
Check the cable between combustion preheater module (CPM) terminal #11 and water pump terminal 1. Check for an intermittent open-circuit.
Remedy as necessary.
Other information
- See Connecting the breakout box
- See Signal specification
- For cars manufactured up to w38 2001 inclusive, see Fuel pump, auxiliary heater, replacing For cars manufactured from w39 2001 inclusive, see Fuel pump auxiliary heater, replacing
- See Contents
- Continue
Refer to Verification
Check the fuel pump (FP) and combustion preheater module (CPM) connectors. Check for contact resistance and oxidation. Remedy as necessary Check for damage in particular.
Measure between the overheat protection thermostat terminals using an ohmmeter. The resistance must be approximately 0 Ω.
The overheat protection thermostat must be replaced if the value is not correct.
Check the cable between combustion preheater module (CPM) terminal #13 and fuel pump (FP) terminal 2. Check for an open-circuit. Check for an short-circuit to ground.
Check the cable between combustion preheater module (CPM) terminal #11 and fuel pump terminal 1. Check for an open-circuit.
The fuel pump (FP) must be replaced if no faults are found in the cable.
Diagnostic trouble code (DTC) CEM-5F3B and/or diagnostic trouble code (DTC) CEM-5F3D may also be stored if there is a fault in the power cable.
Remedy as necessary.
Other information
- See Connecting the breakout box
- See Signal specification
- 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 .
- For cars manufactured up to w38 2001 inclusive, see Fuel pump, auxiliary heater, replacing For cars manufactured from w39 2001 inclusive, see Fuel pump auxiliary heater, replacing
- See Contents
- Continue
Refer to Verification