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 the air conditioning (A/C) pressure sensor.
- Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 1 and ground.

The ohmmeter should read approx. 0 Ohms.

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

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





Checking Engine Control Module Connector

- Ignition OFF.
- A/C pressure sensor disconnected.
- Check engine control module (ECM) connector for contact resistance, oxidation and remedy.
- Engine control module (ECM) connected.
- Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 1 and ground.

The ohmmeter should read approx. 0 Ohms.

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

If reading is incorrect:
- Check cable between air conditioning (A/C) pressure sensor terminal 1 and engine control module (ECM) #B28 for an open-circuit.
- Then proceed to Verification section below.





Checking Signal Cable

- Ignition ON.
- A/C pressure sensor disconnected.
- Connect a voltmeter between air conditioning (A/C) pressure sensor connector terminal 2 and ground.

The voltmeter should read approx. 0 Volts.

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

If reading is Incorrect:
- Check cable between A/C pressure sensor terminal 2 and engine control module (ECM) #B9 for a short- circuit to supply voltage.
- Then proceed to Verification section below.





Checking Signal Cable Resistance

- Ignition OFF.
- A/C pressure sensor disconnected.
- Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 2 and ground.

The ohmmeter should read approx. 10K Ohms.

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

If reading is incorrect:
- Check cable between A/C pressure sensor terminal 2 and engine control module (ECM) #B9 for an open- circuit.
- Then proceed to Verification section below.





Checking the Air Conditioning Pressure Sensor

- Ignition OFF.
- Connect air conditioning (A/C) pressure sensor.
- START the engine and idle it.
- A/C button ON.
- Blower fan ON.
- Go into scrolling value list.
- Read off A/C pressure sensor signal.

Voltage should increase when the A/C compressor starts.

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

If reading is incorrect:
- Try a new air conditioning (A/C) pressure sensor.
- Then proceed to Verification section below.





Verification

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

- Ignition OFF.
- Air conditioning (A/C) pressure sensor and engine control module (ECM) connected.
- START the engine and idle it.
- A/C button ON.
- Blower fan ON.
- Wait until the air conditioning (A/C) compressor has started.
- Read off diagnostic trouble codes (DTCs).

If EFI-225 is stored it should have Intermittent Fault Status.

Alternative Intermittent:
- Fault corrected

Alternative Permanent:
- 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.