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, see Component resistance values Component Resistance Values.
Check cable between control module #16 and engine coolant temperature sensor signal terminal 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.
- To access/replace 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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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.
- To access/replace 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
FAULT-TRACING FAILED - DONE
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