Signal Too Low
Signal too low
Checking the function of the combustion fan
- Ignition on
- Activate the combustion fan.
Listen for a buzzing sound which indicates that the combustion fan is running.
Does the combustion fan function?
Yes - Intermittent fault
No - Checking the connectors
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Checking the connectors
- Ignition off
- Check the electrical terminals on the combustion fan and the control module connector. Check for contact resistance and oxidation and remedy.
Check for damage carefully
- Reinstall the components, reconnect the connectors etc.
- Ignition on
- Activate the combustion fan.
Listen for a buzzing sound which indicates that the combustion fan is running.
If the combustion fan now operates, the cause of the fault was loose connections in the connectors.
Other information:
- To access the control module or connect the breakout box, see Connecting the breakout box Connecting the Breakout Box
- To access the combustion fan, see Fuel injection nozzle / fan motor / pressure equalizer, replacing Fuel Injection Nozzle / Fan Motor / Pressure Equalizer, Replacing
- Checking wiring and terminals Checking Wiring And Terminals.
Does the combustion fan function?
Yes - Fault Found
No - Checking components and wiring
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Checking components and wiring
Check the cable between control module terminal #10 and the signal terminal for the combustion fan (the black lead from the fan). Check for an open-circuit. Check for a short-circuit to ground.
Check the cable between control module terminal #11 and the voltage terminal for the combustion fan (the red cable from the fan). Check for an open-circuit.
If no faults are found in the wiring, the combustion fan must be replaced. See Fuel injection nozzle / fan motor / pressure equalizer, replacing Fuel Injection Nozzle / Fan Motor / Pressure Equalizer, Replacing.
Note! Diagnostic trouble code (DTC) CEM-5F3A Water pump, signal and / or diagnostic trouble code (DTC) CEM-5F3F Fuel pump (FP), signal may be stored in the event of a fault in the power cable.
Remedy as necessary.
Other information:
- To access the control module or connect the breakout box, see Connecting the breakout box Connecting the Breakout Box
- For other values, see Signal specification Signal Specification
- Checking wiring and terminals Checking Wiring And Terminals.
Continue - Verification
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Verification
Verification
Verification
Hint: After the repair it is necessary to check that the fault has been rectified.
- Ignition off.
- Connect connector, install components etc.
- Ignition on.
- Activate the heater fan.
Listen for a buzzing sound indicating that the heater fan is working.
Is the heater fan working?
Yes - VERIFIED
No - VERIFICATION FAILEDPAPER
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VERIFICATION FAILED - Fault-tracing information
VERIFIED - Fault Found
PAPER - No Fault Found
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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 - FAULT-TRACING FAILED
No - Attempt New Test
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FAULT-TRACING FAILED - FAULT-TRACING FAILED
Attempt New Test - Checking the function of the combustion fan
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Intermittent fault
Check the electrical terminals on the combustion fan and the control module connector. Check for contact resistance and oxidation.
Check the cable between control module terminal #10 and the signal terminal for the combustion fan (the black lead from the fan). Check for an intermittent open-circuit. Check for an intermittent short-circuit to ground.
Check the cable between control module terminal #11 and the voltage terminal for the combustion fan (the red cable from the fan). Check for an intermittent open-circuit.
Remedy as necessary.
Other information:
- To access the control module or connect the breakout box, see Connecting the breakout box Connecting the Breakout Box
- To access the combustion fan, see Fuel injection nozzle / fan motor / pressure equalizer, replacing Fuel Injection Nozzle / Fan Motor / Pressure Equalizer, Replacing
- For other values, see Signal specification Signal Specification
- Checking wiring and terminals Checking Wiring And Terminals.
Continue - Fault-tracing information
DONE
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Fault-tracing information
Information
Fault-tracing information
If the fault is intermittent, do not verify fault-tracing if the fault does not recur.
It is possible to view the information again, or leave fault-tracing for this diagnostic trouble code (DTC).
Do you want to view the information again?
Yes - Attempt New Test
No - Fault Found
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Attempt New Test - Checking the function of the combustion fan
DONE - DONE
FAULT FOUND - Fault Found
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