Faulty Signal

Faulty signal

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. A diagnostic trouble code (DTC) for the 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
- Checking wiring and terminals Checking Wiring And Terminals
- Connecting the breakout box, B5254T2 Connecting the Test Box
- Temperature sensor engine coolant, replacing Service and Repair
- Component specifications Specifications
- Signal specification Signal Specification









Were any faults found in the ground cable?

Yes - Verification

No - Checking engine coolant temperature (ECT)

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Checking 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 system
- 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 thermostat

No - Replacing the component

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Checking 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 the temperature is 85 °C or lower when the fan stops, the thermostat is damaged.








°
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:
Thermostat, replacing Service and Repair





Continue - FAULT FOUND

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Replacing the component
Try a new engine coolant temperature (ECT) sensor:
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.








- Ignition off
- Reconnect the connectors, reinstall components etc.
- Ignition on
- Read off the engine coolant temperature (ECT) sensor.





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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