Signal Too Low. Permanent Fault

Checking Power Cable
- Ignition off.
- Disconnect the A/C pressure sensor.
- Ignition on.
- Connect a voltmeter between A/C pressure sensor connector terminal 3 and ground.
- The voltmeter should read 5 Volts.

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

If value is lower:
^ Proceed to Checking Power Cable Resistance To Ground section below.

If value is higher:
^ The A/C pressure sensor power cable is connected inside the engine control module (ECM) to the tank pressure sensor and accelerometer power cables. If anything happens to any of these cables all three will be affected. They should always be checked. Check wiring between: Accelerometer terminal 1 and engine control module # B1, A/C pressure sensor terminal 3 and engine control module # B29, tank pressure sensor terminal 1 and engine control module # B15 for a short-circuit.
^ Then proceed to Verification section below.





Checking Signal Cable Resistance
- Ignition off.
- A/C pressure sensor disconnected.
- Connect an ohmmeter between the A/C pressure sensor connector terminal 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 # B9 for a short-circuit to ground.
^ Then proceed to Verification section below.





Checking The A/C Pressure Sensor
- Ignition off.
- Connect the A/C pressure sensor.
- Start the engine and idle it.
- A/C switch 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) was caused by loose connections in the A/C pressure sensor connector. Check connector for contact resistance and oxidation and remedy.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Try a new A/C pressure sensor.
^ Then proceed to Verification section below.





Checking Power Cable Resistance To Ground
- Ignition off.
- A/C pressure sensor disconnected.
- Wait for approx. 150 seconds (cars with immobilizer 245 seconds).
- Connect an ohmmeter between the A/C pressure sensor connector terminal 3 and ground.
- The ohmmeter should read approx. 0.2 - 1.5K ohms.

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

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





Checking Accelerometer
- Ignition off.
- A/C pressure sensor disconnected.
- Disconnect accelerometer.
- Connect an ohmmeter between the A/C pressure sensor connector terminal 3 and ground.
- The ohmmeter should read approx. 0.2 - 1.5K ohms.

If reading is OK:
^ Try a new accelerometer.
^ Then proceed to Verification section below.

If reading is incorrect:
^ If the car has a leak proceed to test step below.
^ If the car does not have a leak proceed to Checking Power Cables section below.





Checking Fuel Tank Pressure Sensor
- Ignition off.
- A/C pressure sensor disconnected.
- Accelerometer disconnected.
- Disconnect fuel tank pressure sensor.
- Connect an ohmmeter between the A/C pressure sensor connector terminal 3 and ground.
- The ohmmeter should read approx. 0.2 - 1.5K ohms.

If reading is OK:
^ Try a new tank pressure sensor.
^ Then proceed to Verification section below.

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





Checking Power Cables
- The A/C pressure sensor power cable is connected inside the engine control module to the tank pressure sensor and accelerometer power cables. If anything happens to any of these cables all three will be affected.

Check wiring between:
- Accelerometer terminal 1 and engine control module # B1.
- A/C pressure sensor terminal 3 and engine control module # B29.
- Tank pressure sensor terminal 1 and engine control module # B15 for a short-circuit to ground.

Then continue with:
^ ^ Then proceed to Verification section below.





Checking The Engine Control Module Connector
- Ignition off.
- A/C pressure sensor disconnected.
- Check engine control module connector for contact resistance and oxidation and remedy.
- Engine control module connected.
- Connect an ohmmeter between the A/C pressure sensor connector terminal 3 and ground.
- The ohmmeter should read approx. 0.2 - 1.5K ohms.

If reading is OK:
^ The diagnostic trouble code was caused by loose connections in the engine control module connector.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Check cable between A/C pressure sensor terminal 3 and engine control module # B29 for an open-circuit.
^ Then proceed to Verification section below.





Verification
- After carrying out the repair, check that the fault has been remedied as follows.
- Ignition off.
- A/C pressure sensor and engine control module connected.
- Start the engine and idle it.
- A/C switch on.
- Blower fan on.
- Wait until the A/C compressor has started.
- Read off diagnostic trouble codes.
- If EFI-225 is stored it should have the status intermittent fault.

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 Power Cable section above.