Signal Too Low
Signal too low
Checking the function of the fuel pump (FP)
- Ignition on.
Note! It is important that only the ignition is on in order for the heater to start.
- Activate the heater.
A buzzing sound should be heard from the heater.
Check the function of the heater. See Engine coolant heater, test running Engine Coolant Heater, Test Running.
Other information:
- For a description of parameters, see Description of parameters Description of Parameters
- For a description of activations, see Activating components/functions Activating Components/Functions.
Does the heater operate?
Yes - Intermittent fault
No - Checking the connectors
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Checking the connectors
- Ignition off
- Check the fuel pump (FP) and the control module connectors. Check for contact resistance and oxidation and remedy.
Check for damage carefully
- Reinstall the components, reconnect the connectors etc.
- Ignition on.
Note! It is important that only the ignition is on in order for the heater to start.
- Activate the heater.
A buzzing sound should be heard from the heater.
Check the function of the heater. See Engine coolant heater, test running Engine Coolant Heater, Test Running.
If the heater now functions, 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 or replace the fuel pump (FP), see Fuel pump auxiliary heater, replacing Service and Repair
- For other values, see Signal specification Signal Specification
- Checking wiring and terminals Checking Wiring And Terminals.
Does the heater operate?
Yes - Fault Found
No - Checking the overheat protection thermostat
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Checking the overheat protection thermostat
- Ignition off.
Measure between the overheat protection thermostat terminals using an ohmmeter. The resistance must be approximately 0 ohms.
The overheat protection thermostat must be replaced if the value is not correct.
Other information:
- To access or replace the overheat protection thermostat, see Overheat protection thermostat / flame sensor / engine coolant temperature sensor, replacing Service and Repair.
Was a fault detected?
Yes - Verification
No - Checking components and wiring
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Checking components and wiring
Check the cable between control module terminal #13 and fuel pump terminal 2. Check for an open-circuit. Check for a short-circuit to ground.
Check the cable between control module terminal #11 and fuel pump (FP) terminal 1. Check for an open-circuit.
Replace the fuel pump (FP) if no fault is found in the wiring.
Note! Diagnostic trouble code (DTC) CEM-5F3B Water pump, signal and / or diagnostic trouble code (DTC) CEM-5F3D Combustion fan, signal may also be stored if there is 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
- To access or replace the fuel pump (FP), see Fuel pump auxiliary heater, replacing Service and Repair
- 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.
Note! It is important that only the ignition is on for the heater to start up.
- Activate the heater.
A buzzing sound should be heard from the heater.
Check the function of the heater as described in Engine coolant heater, test running Engine Coolant Heater, Test Running.
Additional information:
- For a description of the parameters, see Description of parameters Description of Parameters.
- For a description of activations, see Activating components/functions Activating Components/Functions.
Does the heater work?
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 fuel pump (FP)
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Intermittent fault
Check the fuel pump (FP) and the control module connectors. Check for contact resistance and oxidation.
Check the cable between control module terminal #13 and fuel pump terminal 2. Check for an intermittent open-circuit. Check for a short-circuit to ground.
Check the cable between control module #11 and water pump terminal 1. 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 or replace the fuel pump (FP), see Fuel pump auxiliary heater, replacing Service and Repair
- 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 fuel pump (FP)
DONE - DONE
FAULT FOUND - Fault Found
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