FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
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Flame Interruption






Flame interruption

Checking the function of the flame sensor




- Ignition on.

Note! It is important that only the ignition is on in order for the heater to start.

- Activate the heater.
Listen for a buzzing sound which indicates that the heater is running.
Check the heater function.

Other information
- Engine coolant heater, test running Component Tests and General Diagnostics





Does the heater start?

Yes - Checking components and wiring

No - Checking components and wiring

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Verification




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








- Ignition off
- Reinstall the connectors, components etc.
- Ignition on
- Read off the engine coolant temperature.

Note! It is important that only the ignition is on in order for the heater to start.

- Activate the heater.

Hint: After repair, the voltage of the flame sensor can be checked. The voltage must be a maximum of 1.0 V.

Check the heater function.

Caution! In order for to enable start of the heater itself, the battery voltage must be normal, coolant temperature must be lower than +96 °C and the heater's after-run/stop sequence must be finished. There must also be enough fuel in the tank.

Caution! If the heater or other components are not activated, try closing down the activation window and then starting the activation again with the symbol for VCT2000.

Other information:
- Engine coolant heater, test running Component Tests and General Diagnostics.





Is the heater working?

Yes - VERIFIED

No - VERIFICATION FAILEDPAPER

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VERIFIED - Fault Found

VERIFICATION FAILED - 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 - 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 flame sensor

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Checking components and wiring
Check the cable between central electronic module (CEM) terminal #8 and the signal cable for the flame sensor. Check for a short-circuit to supply voltage. Check for an open-circuit.

Hint: It is difficult to differentiate between the ground lead for the flame sensor and the signal cable. Take readings on one cable at a time to check for a plausible value on either of them.

Replace the flame sensor if no fault is found in the cable.
Remedy as necessary.

Other information
- Connecting the breakout box Connecting the Breakout Box
- Signal specification Signal Specification
- Overheat protection thermostat / flame sensor / engine coolant temperature sensor, replacing Service and Repair
- Checking wiring and terminals Checking Wiring And Terminals










Continue - Verification

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Checking components and wiring
Check the central electronic module (CEM) connector. Check for contact resistance and oxidation.
Check the flame sensor circuit. Check for an intermittent open-circuit.
Check the cable between central electronic module (CEM) terminal #8 and the signal terminal for the flame sensor. Check for an intermittent short-circuit to supply voltage.
Remedy as necessary.

Other information
- Connecting the breakout box Connecting the Breakout Box
- Signal specification Signal Specification
- Overheat protection thermostat / flame sensor / engine coolant temperature sensor, replacing Service and Repair
- Checking wiring and terminals Checking Wiring And Terminals









Continue - Verification

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