Signal Too Low - Permanent Fault

ECM-2000 ENGINE COOLANT TEMPERATURE (ECT) SENSOR
SIGNAL TOO LOW - PERMANENT FAULT

Checking connector




WARNING!
Before fault-tracing can begin, the engine cooling fan (FC) connector must be disconnected to prevent the engine cooling fan (FC) engaging. Diagnostic Trouble Code (DTC) ECM-6110 Engine cooling fan (FC) low-speed signal may be stored. After fault-tracing the connector must be reconnected.

- Ignition off
- Check the engine coolant temperature (ECT) sensor connector for contact resistance and oxidation according to [1][2]Checking Wiring and Terminals. Permanent Fault
- Reinstall components, reconnect connectors etc.
- Ignition on.
- Read off the engine coolant temperature (ECT) sensor.

If the temperature is now within its permitted range, the fault was caused by loose connections in the connector.

Other information
- To access the engine coolant temperature (ECT) sensor, Engine Temperature Sensor, Replacing

Is the temperature within its permitted range?
Yes - Testing Complete.
No - Continue below.


Checking wiring and components



Check engine coolant temperature (ECT) sensor resistance.

NOTE: The engine coolant temperature (ECT) sensor may be defective as a result of the signal cable having been short-circuited to supply voltage. Check this before replacing the sensor.

Check the signal cable between control module #A4 (#A4) engine coolant temperature (ECT) sensor #1 for an open-circuit according to [1][2]Checking Wiring and Terminals. Permanent Fault and a short-circuit to supply voltage according to [1][2]Checking Wiring and Terminals. Permanent Fault

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

Check ground lead between control module #A60 (#A60) and engine coolant temperature (ECT) sensor #2 for an open-circuit according to [1][2]Checking Wiring and Terminals. Permanent Fault
Remedy as necessary.

Other information
- Connecting the breakout box/accessing the control module, Connecting the Breakout Box (ECM)
- To access the engine coolant temperature (ECT) sensor, Engine Temperature Sensor, Replacing
- For resistance values, see Component Specifications. Specifications
- For information about signals, see Diagnostic Parameters and Pinout Values. Signal Description, ME7, B5XX4T


Verification




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

- Ignition off.
- Reconnect connectors, reinstall components
- Ignition on.
- Read off the engine coolant temperature (ECT) sensor.

Is the temperature within its permitted range?
Yes - Testing Complete.
No - Continue below.


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.