Signal Too Low
Signal too low
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 component and cables
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Checking component and cables
Check engine coolant temperature sensor resistance. For resistance values refer to Component resistance values Component Resistance Values.
Check cable between control module #16 and the engine coolant temperature (ECT) sensor signal connection for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Hint: Because it is difficult to separate the engine coolant temperature sensor ground lead from the signal cable, one must measure one cable at a time and see if the permitted values are present on either of them.
Remedy as necessary.
Other information:
- To access the control module/connect breakout box see Pinout Values and Diagnostic Parameters.
- To access/replace Coolant temperature sensor see Overheating protection thermostat, flame sensor and Coolant temperature sensor, replace Service and Repair.
- With ignition on and engine coolant temperature sensor signal cable cut the voltage between 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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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 - 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 cable between control module #16 and engine coolant temperature sensor signal terminal for an intermittent short-circuit to ground 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 Pinout Values and Diagnostic Parameters.
- To access/replace Coolant temperature sensor see Overheating protection thermostat, flame sensor and Coolant temperature sensor, replace 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
FAULT-TRACING FAILED - DONE
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