Signal Too Low

Signal too low

Checking the components and wiring

Warning! The engine cooling fan (FC) can also operate if the ignition is switched off when this diagnostic trouble code (DTC) is stored.

Hint: To avoid injury, disconnect the power supply to the engine cooling fan (FC) during fault-tracing.

- Check the connector on the engine coolant temperature (ECT) sensor. Check for contact resistance and oxidation.
Check the resistance of the engine coolant temperature (ECT) sensor. Take readings between terminals #1 and #2 on the engine coolant temperature (ECT) sensor.
Check signal cable for an open-circuit and short-circuit to supply voltage.
Take readings between:
- Engine Control Module (ECM) #A42 (#A42) and engine temperature sensor #1.

Hint: With the ignition on and engine coolant temperature (ECT) sensor connector disconnected the voltage between terminal #1 and ground terminal should be approximately 5 V.

Check the ground lead. Check for an open-circuit.
Take readings between:
- Engine Control Module (ECM) #A12 (#A12) and engine temperature sensor #2.
Remedy as necessary.

Other information
- Connecting the breakout box, B5254T7 Connecting The Breakout Box, Engine Control Module (ECM)
- Signal specification, B5254T7 Signal Specification, Engine Control Module (ECM)
- Component specifications, B5254T7 Specifications
- Engine coolant temperature sensor (ECT), B5254T7 Service and Repair
- Checking wiring and terminals Checking Wiring and Terminals













Continue - Verification

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Verification




Verification

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








- Verification should begin with a cold engine (+20 °C) so that the engine coolant temperature (ECT) sensor can be tested over as wide a temperature range as possible
- Ignition off
- Reconnect the connectors, reinstall components etc.
- Start the engine.
Read off the engine coolant temperature (ECT) sensor signal.
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 - Troubleshooting procedure complete

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 components and wiring

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