Signal Too High. Permanent Fault

SIGNAL TOO HIGH. PERMANENT FAULT





Checking Ground Lead

- Ignition OFF.
- Wait for approx. 150 seconds (cars with immobilizer 245 seconds).
- Disconnect outside temperature sensor (blue connector).
- Connect an ohmmeter between outside temperature sensor connector terminal 2 and ground.

The ohmmeter should read approx. 0 Ohms.

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

If reading is incorrect:
- Proceed to Checking Engine Control Module Connector - Ground section below.





Checking Signal Cable

- Ignition ON
- Temperature sensor disconnected.
- Connect a voltmeter between temperature sensor connector terminals 1 and 2 (engine control module (ECM) side).

The voltmeter should read approx. 5 Volts.

If reading is OK:
- Proceed to Checking Temperature Sensor Resistance section below.

If value is Lower:
- Proceed to Checking Engine Control Module Connector - Supply section below.

If value is Higher:
- Proceed to test step below.





Checking for a Short-Circuit

- Check cable between outside temperature sensor terminal 1 and engine control module (ECM) #A35 for a short-circuit to voltage supply.

Then proceed to Checking the Outside Temperature Sensor section below.





Checking Engine Control Module Connector - Ground

- Ignition OFF.
- Temperature sensor disconnected.
- Check engine control module (ECM) connector for contact resistance, oxidation and remedy.
- Engine control module (ECM) connected.
- Connect an ohmmeter between temperature sensor connector terminal 2 (engine control module (ECM) side) and ground.

The ohmmeter should read approx. 0 Ohms.

If reading is OK:
- The diagnostic trouble code (DTC) has been caused by loose connections in the engine control module (ECM) connector.
- Then proceed to Verification section below.

If reading is incorrect:
- Check cable between the temperature sensor terminal 2 and engine control module (ECM) #A18 for an open-circuit.
- Then proceed to Verification section below.





Checking Temperature Sensor Resistance

- Ignition OFF.
- Temperature sensor disconnected.
- Connect an ohmmeter between temperature sensor connector terminals 1 and 2 (temperature sensor side).





The ohmmeter should read approx. 500 Ohms at +25°C (77°F) (see image).

If reading is OK:
- The diagnostic trouble code (DTC) has been caused by loose connections in the outside temperature sensor connector.
- Check connector for contact resistance, oxidation and remedy.
- Then proceed to Verification section below.

If reading is incorrect:
- Try a new outside temperature sensor.
- Then proceed to Verification section below.





Checking the Outside Temperature Sensor

Hint: The outside temperature sensor can malfunction due to a short-circuit to supply voltage in the signal cable. Check the temperature sensor as follows:

- Ignition OFF.
- Temperature sensor disconnected.
- Connect an ohmmeter between temperature sensor connector terminals 1 and 2 (temperature sensor side).





The ohmmeter should read approx. 500 Ohms at +25°C (77°F) (see image).

If reading is OK:
- Temperature sensor is OK.
- Then proceed to Verification section below.

If reading is incorrect:
- Try a new outside temperature sensor.
- Then proceed to Verification section below.





Checking Engine Control Module Connector - Supply

- Ignition OFF.
- Temperature sensor disconnected.
- Check engine control module (ECM) connector for contact resistance, oxidation and remedy.
- Engine control module (ECM) connected.
- Ignition ON
- Connect a voltmeter between temperature sensor connector terminals 1 and 2 (engine control module (ECM) side).

The voltmeter should read approx. 5 Volts.

If reading is OK:
- The diagnostic trouble code (DTC) has been caused by loose connections in the engine control module (ECM) connector.
- Then proceed to Verification section below.

If reading is incorrect:
- Check cable between temperature sensor terminal 1 and engine control module (ECM) #A35 for a short-circuit to voltage supply.
- Then proceed to Verification section below.





Verification

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

- Ignition OFF.
- Reconnect connectors, reinstall components etc.
- Ignition ON.
- Go into scrolling value list.
- Read off outside temperature.

NOTE! If the radiator is hot the outside temperature sensor will heat up if the car is stationary.

Is the outside temperature value within bounds?

Yes:
- Fault corrected

No:
- 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 Ground Lead section above.