Signal Too High. Permanent Fault

Checking Ground Lead
- Ignition OFF.
- Wait for approximately 150 seconds (cars with immobilizer 245 seconds).
- Disconnect right outside temperature sensor.
- Connect an ohmmeter between outside temperature sensor connector terminal 2 and ground.
- The ohmmeter should read approximately 0 ohms.

If reading is OK:
^ Proceed to: Checking the Signal Cable section below.

If reading is incorrect:
^ Proceed to: Checking Control Module Connector section below.





Checking the 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 approximately 5 Volts.

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

If value is lower:
^ Proceed to: Checking Control Module Connector section below.

If value is higher:
^ Proceed to: Checking for a Short-Circuit section below.





Checking for a Short-Circuit
- Check cable between outside temperature sensor terminal 1 and engine control module # A35 for a short-circuit to voltage supply.
- Proceed to: Checking the Outside Temperature Sensor section below.





Checking Control Module Connector
- Ignition OFF.
- Temperature sensor disconnected.
- Check control module connector for contact resistance and oxidation and remedy.
- Control module connected.
- Connect an ohmmeter between temperature sensor connector terminal 2 (engine control module side) and ground.
- The ohmmeter should read approximately 0 ohms.

If reading is OK:
^ Proceed to: Fault-tracing Information section below.

If reading is incorrect:
^ Proceed to: Checking for an Open-Circuit section below.

Fault-tracing Information
- The cause of the diagnostic trouble code (DTC) has been loose connections in the control module connector.
- Proceed to: Verification section below.





Checking for an Open-Circuit
- Check cable between temperature sensor terminal 2 and engine control module # A18 for an open- circuit.
- 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 approximately 500 ohms at +25°C (+77°F) (see image).

If reading is OK:
^ Proceed to: Checking for Contact Resistance and Oxidation section below.

If reading is incorrect:
^ Proceed to: Replacing Component section below.

Checking for Contact Resistance and Oxidation
- The diagnostic trouble code has been caused by loose connections in the outside temperature sensor connector.
- Check connector for contact resistance and oxidation and remedy.
- Proceed to: Verification section below.

Replacing Component
- Try a new outside temperature sensor.
- Proceed to: Verification section below.





Checking the Outside Temperature Sensor
- 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 approximately 500 ohms at +25°C (+77°F) (see image).

If reading is OK:
^ Proceed to: Fault-tracing Information section below.

If reading is incorrect:
^ Proceed to: Replacing Component section below.

Fault-tracing Information
- Temperature sensor is OK.
- Proceed to: Verification section below.

Replacing Component
- Try a new outside temperature sensor.
- Proceed to: Verification section below.





Checking Control Module Connector
- Ignition OFF.
- Temperature sensor disconnected.
- Check control module connector for contact resistance and oxidation and remedy.
- Control module connected.
- Ignition ON.
- Connect a voltmeter between temperature sensor connector terminals 1 and 2 (engine control module side).
- The voltmeter should read approximately 5 Volts.

If reading is OK:
^ Proceed to: Fault-tracing Information section below.

If reading is incorrect:
^ Proceed to: Checking for an Open-Circuit section below.

Fault-tracing Information
- The cause of the diagnostic trouble code has been loose connections in the control module connector.
- Proceed to: Verification section below.





Checking for an Open-Circuit
- Check cable between temperature sensor terminal 1 and engine control module # A35 for a short- circuit to voltage supply.
- 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.
- Ignition ON.
- Select Volvo Scan Tool (ST) to read off the 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:
^ Fault not found.