Signal Too High. Permanent Fault

Checking Ground Lead
- Ignition OFF.
- Wait for approx. 150 seconds (cars with immobilizer 245 seconds).
- Disconnect the air conditioning (A/C) pressure sensor.
- Connect an ohmmeter between air conditioning pressure sensor connector 1 and ground.
- The ohmmeter should read approx. 0 ohms.

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

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





Checking ECM Connector
- Ignition OFF.
- Air conditioning pressure sensor disconnected.
- Check engine control module (ECM) connector for contact resistance and oxidation and remedy.
- Engine control module connected.
- Connect an ohmmeter between air conditioning pressure sensor connector 1 and ground.
- The ohmmeter should read approx. 0 ohms.

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

If reading is incorrect:
^ Check cable between air conditioning pressure sensor terminal 1 and engine control module # B28 for an open-circuit.
^ Proceed to: Verification section below.





Checking the Signal Cable
- Ignition ON.
- Air conditioning pressure sensor disconnected.
- Connect a voltmeter between air conditioning pressure sensor connector 2 and ground.
- The voltmeter should read approx. 0 Volts.

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

If reading is incorrect:
^ Check cable between air conditioning pressure sensor terminal 2 and engine control module # B9 for a short-circuit to supply voltage.
^ Proceed to: Verification section below.





Checking Signal Cable Resistance
- Ignition OFF.
- Air conditioning pressure sensor disconnected.
- Connect an ohmmeter between air conditioning pressure sensor connector 2 and ground.
- The ohmmeter should read approx. 10 k ohms.

If reading is OK:
^ Proceed to: Checking A/C Pressure Sensor section below.

If reading is incorrect:
^ Check cable between air conditioning pressure sensor terminal 2 and engine control module # B9 for an open-circuit.
^ Proceed to: Verification section below.





Checking A/C Pressure Sensor
- Ignition OFF.
- Connect air conditioning pressure sensor.
- Start the engine and idle it.
- Air conditioning switch ON.
- Blower fan ON.
- Go into scrolling values.
- Read off air conditioning pressure sensor signal.
- Voltage should increase when the air conditioning compressor starts.

If reading is OK:
^ The cause of the diagnostic trouble code (DTC) has been loose connections in the air conditioning pressure sensor connector.
^ Check connector for contact resistance and oxidation and remedy.
^ Proceed to: Verification section below.

If reading is incorrect:
^ Try a new air conditioning pressure sensor.
^ Proceed to: Verification section below.





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

- Ignition OFF.
- Air conditioning pressure sensor and engine control module connected.
- Start the engine and idle it.
- Air conditioning switch ON.
- Blower fan ON.
- Wait until the air conditioning compressor has started.
- Read off any diagnostic trouble codes.
- If EFI-225 is stored it should have intermittent fault status.

If reading is OK:
^ Fault corrected.

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

Fault-tracing Information
The verification result shows that the fault persists.

- Do you want to exit fault-tracing?

Yes:
^ Fault not corrected.

No:
^ Proceed to: Checking Ground Lead section above.