Faulty Signal. Permanent Fault

Faulty signal. Permanent fault

Checking the wiring

Warning! Before fault-tracing can begin, the engine cooling fan (FC) connector must be disconnected to prevent the engine cooling fan (FC) engaging. Diagnostic trouble code (DTC) ECM-6120 Engine cooling fan (FC) control module may be stored. After fault-tracing the connector must be reconnected.

Note! This diagnostic trouble code (DTC) is stored if the engine coolant temperature (ECT) sensor freezes. This may happen if the coolant level is low or there is too little glycol in the coolant. Check the engine coolant level and its freezing point. Remedy as necessary.








- Ignition off
- Check the ground lead between control module terminal #A60 (#A60) and engine coolant temperature (ECT) sensor terminal #2. Check for an open-circuit
- Reinstall the components, reconnect the connectors etc.

Other information
- To connect the breakout box / access the control module, see Connecting the breakout box, B5254T2 Connecting the Test Box
- To access the engine coolant temperature (ECT) sensor, see Temperature sensor engine coolant, replacing Service and Repair
- For resistance values, see Component specifications Specifications
- For information about signals, see Signal specification Signal Specification
- Checking wiring and terminals Checking Wiring And Terminals.













Were any faults found in the ground cable?

Yes - Verification

No - Checking the engine coolant temperature (ECT)

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Checking the engine coolant temperature (ECT)




- Fault-tracing must begin with the engine cold (+20 °C) so that the engine coolant temperature (ECT) sensor can be tested over as wide a temperature range as possible
- Switch off the climate control unit
- Start the engine.
Read off the engine coolant temperature (ECT).
Check that the engine coolant temperature (ECT) is within its permitted range and corresponds with the engine warming up.









Is the temperature within its permitted range?

Yes - Checking the thermostat

No - Replacing the component

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Checking the thermostat




- Start the engine. Run the engine until the engine coolant temperature (ECT) reaches approximately 100°C
- Activate the engine cooling fan (FC) with the engine running
- Wait approximately 90 seconds and then shut-off the engine cooling fan (FC).
Read off the engine coolant temperature (ECT). If it is 85°C or lower when the fan stops, the thermostat is defective.








°
Is the temperature lower than 86C?

Yes - Replacing the component

No - FAULT-TRACING FAILED

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Replacing the component
Try a new thermostat. See Thermostat, replacing Service and Repair.





Continue - FAULT FOUND

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Replacing the component
Try a new engine coolant temperature (ECT) sensor. See Temperature sensor engine coolant, replacing Service and Repair.





Continue - Verification

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Verification




Verification

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








- Fault-tracing must begin with the engine cold (+20 °C) so that the engine coolant temperature (ECT) sensor can be tested over as wide a temperature range as possible
- Ignition off
- Reconnect connectors, reinstall components etc.
- Start the engine
- Read off the engine coolant temperature.
Check that the engine coolant temperature (ECT) is within its permitted range and corresponds with the engine warming up.





Is the temperature within its permitted range?

Yes - Verification completed

No - 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 - Exit Fault-Tracing

No - Attempt New Test

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Attempt New Test - Checking the wiring

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