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
- 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 - VERIFIED

No - VERIFICATION FAILED

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VERIFICATION FAILED - Fault-tracing information

VERIFIED - FAULT FOUND

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Fault-tracing information

Attempt New Test - Checking the components and wiring

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