Signal Too High

Signal too high

Checking engine coolant temperature (ECT) sensor function




- Ignition on.
- Read off coolant temperature.
Check the engine coolant temperature (ECT) reading is correct. Compare with the actual coolant temperature of the engine.





Is the temperature reading OK?

Yes - Intermittent fault

No - Checking the connectors

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Checking the connectors








- Ignition off.
- Check control module connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Check any damage etc.
- Reinstall components, reconnect connectors etc.
- Ignition on.
- Read off coolant temperature.
Check the engine coolant temperature (ECT) reading is correct. Compare with the actual coolant temperature of the engine.
If the temperature is now OK it means that the fault was caused by loose connections in the connector.

Other information:
- To access the control module/connect breakout box see.





Is the temperature reading OK?

Yes - FAULT FOUND

No - Checking component and cables

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Checking component and cables
Check engine coolant temperature sensor resistance. For resistance values, see Component resistance values Component Resistance Values.
Check cable between control module #4 and engine coolant temperature sensor 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 cables to the engine coolant temperature sensor, measure between control module #4 and both cables to the water temperature sensor.

Check cable between control module #16 and engine coolant temperature sensor signal terminal for an open-circuit 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 cables to the engine coolant temperature sensor test the cables one at a time and see if a relevant value was obtained from either of them.

Note! Diagnostic trouble code (DTC) HEA-142 outside temperature sensor is stored with faults in the ground lead

Remedy as necessary.

Other information:
- To access the control module/connect breakout box see.
- To access/replace the Coolant temperature sensor see Replacing overheat protection, thermostat flame sensor and coolant temperature sensor Service and Repair.
- With ignition on and the engine coolant temperature sensor signal cable cut the voltage between the engine coolant temperature 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.
- Read off coolant temperature.
Check the engine coolant temperature (ECT) reading is correct. Compare with the actual coolant temperature of the engine.





Is the temperature within its permitted range?

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 engine coolant temperature (ECT) sensor function

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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 circuit for an intermittent open-circuit by measuring resistance between control module connector #16 and #4 (towards the sensor) and follow the instructions according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults. Resistance should be according to Component resistance values Component Resistance Values.
Check cable between control module #16 and engine coolant temperature sensor 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 Coolant temperature 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 engine coolant temperature (ECT) sensor function

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