Signal Too High

Signal too high

Checking the status




- Ignition on.
Activate the water pump.
There must be a buzzing sound from the water pump when it is activated.
The fault is permanent if the water pump does not start.
If the water pump starts, this is an indication that the fault was present previously but that it is not active at the moment, i.e. the fault is intermittent.





Continue - Checking the component and wiring

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Checking the component and wiring








- Ignition off
- Disconnect the connector in the heater.
Check the terminals. Check for contact resistance. Check for loose connections. Check for oxidation.
Check the cable between combustion preheater module (CPM) terminal #10 and the water pump terminal. Check for a short-circuit to supply voltage.
Check the cable between combustion preheater module (CPM) terminal #11 and the water pump terminal. Check for a short-circuit to supply voltage.
Remedy as necessary.

Other information
- Signal specification Signal Description, Combustion Preheater Module (CPM)
- Component specification [1][2]Auxiliary Cabin Heater
- Water pump engine coolant heater, replacing Water Pump Engine Coolant Heater, Replacing
- Checking wiring and terminals Checking Wiring and Terminals









Continue - Verification

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Verification




Verification

Hint: After carrying out the repair, check that the fault has been remedied.








- Ignition off
- Reinstall the connectors, components etc.
- Ignition on.
Activate the water pump.
Listen for a buzzing sound which indicates that the water pump is running.





Is the water pump working?

Yes - Troubleshooting procedure complete

No - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit Fault-Tracing

No - Attempt New Test

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Attempt New Test - Checking the component and wiring

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