Too Many Unsuccessful Attempts
Too many unsuccessful attempts
Checking the quantity of fuel and voltage
Hint: A transparent hose can be used to check if fuel supply to the parking heater works.
If the quantity of fuel in the fuel tank is below 6 liters the heater is not permitted to start. If the battery voltage is poor the heater is not permitted to start. The combustion preheater module (CPM) interprets 3 or more failed start attempts as a fault in the heater. The heater cannot then be started until the diagnostic trouble codes (DTCs) have been erased
- Ignition on.
Note! The heater must be switched off when reading off!
Read off the values.
The fuel level status must be OK and the voltage to the heater must be normal.
Other information:
- Combustion preheater module (CPM): Description of parameters
Was a fault detected?
Yes - Verification
No - Checking fuel lines
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Checking fuel lines
Warning! Use protective gloves and protective goggles due to the risk of fuel spillage.
- Release the heater and fuel lines.
Check the fuel lines between the connection point to the fuel injection system and heater via the fuel pump (FP). Check for damage and leakage.
Check the fuel lines for blockages.
Other
- Fuel-powered preheater, checking
- Engine coolant heater, replacing
Was a fault detected?
Yes - Verification
No - Checking components
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Checking components
Warning! Use protective gloves and protective goggles due to the risk of fuel spillage.
- 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 must be heard from the heater
Check whether the fuel pump is operating. The pump should make a ticking sound.
Replace the fuel pump (FP) if it is not working. See: Fuel pump auxiliary heater, replacing
Other information:
- Description of parameters
- Activating components/functions
- Fuel-powered preheater, checking
Did the heater operate?
Yes - Checking the nozzle pipe
No - Verification
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Checking the nozzle pipe
- Engine coolant heater, replacing
- Fuel injection nozzle / fan motor / pressure equalizer, replacing
Check that the nozzle pipe is OK and that it is not blocked.
Remedy as necessary.
Was a fault detected?
Yes - Verification
No - Checking the combustion air flow
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Checking the combustion air flow
- Engine coolant heater, replacing
Check for free air flow through the heater (that the air intake and exhaust are not blocked).
Remedy as necessary.
Was a fault detected?
Yes - Verification
No - Checking the flame sensor
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Checking the flame sensor
Check that the flame sensor is not clogged with soot.
Remedy as necessary.
Other information:
- Overheat protection thermostat / flame sensor / engine coolant temperature sensor, replacing
Was a fault detected?
Yes - Verification
No - Checking components and wiring
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Checking components and wiring
Check the cable between combustion preheater module (CPM) terminal #4 and the ground terminal for the flame sensor. Check for an open-circuit.
Hint: It is difficult to differentiate between the flame sensor cables so take readings between control module terminal #4 and both flame sensor cables.
Check the cable between combustion preheater module (CPM) terminal #8 and the positive cable for the flame sensor. Check for an open-circuit. Check for a short-circuit to supply voltage.
Hint: It is difficult to differentiate between the cables to the flame sensor. Take readings on the cables one at a time and see if a relevant value was obtained from either of them.
If no fault is found in the connectors or cables, try a new flame sensor.
Remedy as necessary.
Other information:
- Connecting the breakout box
- Overheat protection thermostat / flame sensor / engine coolant temperature sensor, replacing
- For other values: Signal specification
- 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.
Erase diagnostic trouble codes (DTCs).
Note! Diagnostic trouble codes (DTCs) must be erased to start the heater. Before erasing diagnostic trouble codes (DTCs) all indicated faults must be corrected.
Numeric Result 0 - Verification, continued
Numeric Result 25456 - Verification, continued
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Verification, continued
- Ignition off
- Reinstall the connectors, components 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.
Hint: After repair, the voltage of the flame sensor can be checked. The voltage should be a maximum of 1.0 V.
Check the function of the heater. See Engine coolant heater, test running .
Other information:
- For a description of parameters, see Description of parameters
- For a description of activations, see Activating components/functions .
Does the heater operate?
Yes - VERIFIED
No - VERIFICATION FAILEDPAPER
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VERIFICATION FAILED - Fault-tracing information
VERIFIED - FAULT FOUND
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Fault-tracing information
Attempt New Test - Checking the quantity of fuel and voltage
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