Signal Too Low. Permanent Fault

SIGNAL TOO LOW. PERMANENT FAULT





Checking Signal Cable

WARNING! Before fault-tracing disconnect Engine Cooling Fan (FC) relay connector A so that the engine cooling fan (FC) will not run. Diagnostic Trouble Code (DTC) EFI-514 engine cooling fan (FC) low-speed, signal may be stored. After fault-tracing the connector must be reconnected.

- Ignition ON.
- Go into scrolling values list.
- Disconnect temperature sensor.
- Read voltage across Engine Coolant Temperature (ECT) Sensor.

The reading should be approx. 5 Volts.

If reading is OK:
- Try a new engine coolant temperature (ECT) sensor.
- Then proceed to Verification section below.

If reading is incorrect:
- Check cable between the engine coolant temperature (ECT) sensor terminal 1 and engine control module (ECM) #A31 for a short-circuit to ground.
- Then proceed to Verification section below.





Verification

- After carrying out the repair, check that the fault has been remedied as follows.
- Ignition OFF.
- Reconnect connectors, reinstall components etc.
- Connect a multimeter 999 6525 with temperature box 999 528 land temperature sensor 999 5282
- Carefully remove the expansion tank cap.

WARNING! The coolant may be hot.

- Clamp the hose between the radiator and thermostat housing using a hose clip and disconnect the hose from the thermostat housing.
- Insert sensor in thermostat housing and reinstall hose.
- Remove hose clip.
- START engine and RUN up to working temperature.
- The engine should be warm enough for the thermostat to open.
- Go into scrolling value list.
- Read engine coolant temperature (ECT).

Is the engine coolant temperature (ECT) value within bounds?

If reading is OK:
- Fault corrected

If reading is incorrect:
- Proceed to test step below.

Fault-Tracing Information

- The verification result shows that the fault persists.
- Do you want to exit fault-tracing?

Yes:
- Fault not corrected

No:
- Return to Checking Signal Cable section above.