Signal Too High
Signal too high
Checking heater function
- Ignition on.
- Activate heater.
Check heater function according to Test driving of Additional heater/Parking heater Initial Inspection and Diagnostic Overview.
Does the heater function?
Yes - Intermittent fault
No - Start attempts
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Intermittent fault
Check control module connector for contact resistance and oxidation in accordance with Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
Check flame sensor circuit for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
Check cable between control module #8 and flame sensor signal terminal for an intermittent short-circuit to supply voltage according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
Remedy as necessary.
Other information:
- To access the control module/connect breakout box see.
- To access/replace the flame sensor see Replacing overheat protection, thermostat flame sensor and coolant temperature sensor Service and Repair.
- For other values, see Signal specification Additional heater 912-D/B Signal Specification Additional Heater 912-D/B.
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 heater function
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Start attempts
Too many unsuccessful
Checking fuel lines
- Remove the lower air baffle.
- Remove soundproofing under engine.
Check the fuel lines between the fuel filter and the heater for damage and leakage.
Remedy as necessary.
Was a fault detected?
Yes - Verification
No - Checking fuel supply to the fuel pump (FP)
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Checking fuel supply to the fuel pump (FP)
Warning! Protective gloves and protective goggles should be used for the following operations because of the risk of fuel spillage.
- Position a container under fuel pump (FP).
- Disconnect fuel line from fuel pump (FP) according to Moving the heater to its service position Procedures
Check if fuel comes out of fuel line. The fuel in the fuel filter may spill out.
If there is no fuel there is a fault in the fuel line to the fuel pump (FP).
Remedy as necessary.
Was a fault detected?
Yes - Verification
No - Checking fuel supply to the heater
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Checking fuel supply to the heater
Warning! Protective gloves and protective goggles should be used for the following operations because of the risk of fuel spillage.
- Ignition on.
- Position a container under fuel pump (FP).
- Move heater to service position according to Moving the heater to its service position Procedures.
- Disconnect fuel hose at fan shroud.
- Reinstall heater except for fuel line at the fan shroud. It should hang straight down.
- Activate heater.
Check if fuel comes out of fuel hose. If fuel comes out the heater should be deactivated.
If no fuel comes out of the fuel line the fuel pump (FP) should be replaced according to Replacing fuel pump Service and Repair.
Was a fault detected?
Yes - Verification
No - Checking nozzle pipe
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Checking nozzle pipe
- Move heater to service position according to Moving the heater to its service position Procedures.
- Disconnect nozzle pipe according to Replacing fuel injection nozzle, fan motor and nozzle pipe Service and Repair.
Check that the nozzle pipe seems OK and that it is not blocked.
Remedy as necessary
Was a fault detected?
Yes - Verification
No - Checking intake air flow
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Checking intake air flow
- Move heater to service position according to Moving the heater to its service position Procedures.
Check that the air flow through the heater is free, that the air intake and exhaust are not blocked.
Remedy as necessary.
Was a fault detected?
Yes - Verification
No - Checking flame sensor
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Checking flame sensor
Check if the flame sensor is clogged with soot.
Remedy as necessary.
Other information:
- To access/replace the flame sensor see Replacing fuel injection nozzle, fan motor and nozzle pipe Service and Repair.
Was a fault detected?
Yes - Verification
No - Checking component and cables
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Checking component and cables
Check cable between control module #4 and flame trap ground terminal for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Hint: Because it is difficult to separate the flame sensor cables measure between control module #4 and both flame sensor cables.
Check cable between control module #8 and flame sensor signal terminal for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault and a short-circuit to supply voltage according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Hint: Because it is difficult to separate the flame sensor cables try to measure one flame sensor cable at a time and see if there is a relevant value on either of them.
If no fault is found in the connectors or cables, try a new flame sensor.
Note! Diagnostic trouble code (DTC) HEA-142 outside temperature sensor signal and/or HEA-801 Coolant temperature sensor signal can be stored if there is a fault in the ground lead
Remedy as necessary.
Other information:
- To access the control module/connect breakout box see.
- To access/replace the flame sensor see Replacing fuel injection nozzle, fan motor and nozzle pipe Service and Repair.
- With ignition on and flame sensor signal cable cut the voltage between flame sensor signal cable (engine control module (ECM) side) and ground should be approximately 5 V.
- For other values, see Signal specification Additional heater 912-D/B Signal Specification Additional Heater 912-D/B.
Continue - Verification
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Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off.
- Reinstall connectors, components etc.
- Ignition on.
- Activate heater.
Check heater function according to Test driving of Additional heater/Parking heater Initial Inspection and Diagnostic Overview.
Does the heater function?
Yes - VERIFIED
No - VERIFICATION FAILED
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VERIFICATION FAILED - Fault-tracing information
VERIFIED - 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 - Exit fault-tracing
No - Attempt New Test
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Attempt New Test - Checking fuel lines
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No Fault Found - No Fault Found
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