DTC 2-2-5

2-2-5 A/C PRESSURE SENSOR, SIGNAL

Preconditions for DTC
^ If the ECM receives a signal from the A/C pressure sensor which corresponds to a pressure above 3100 kPa (500 psi) (high signal) or lower than -81 kPa (-12 psi) (low signal), then DTC 2-2-5 is set.

Substitute value
^ The control module assumes a substitute pressure of 13.5 kPa (1.96 psi).
^ The engine cooling fan runs at half-speed.

Fault sources
^ Signal too high:
- Signal lead short circuited to voltage supply.
- Break in signal or ground lead.
- Contact resistance in connections.
- Defective NC pressure sensor.

^ Signal too low:
- Signal lead short circuited to ground.
- Defective A/C pressure sensor.

Fault symptoms
^ A/C compressor stops or is prevented from starting.

TESTING PROCEDURE





Status Message
^ Check current status message.

If Status message is: Permanent fault, signal too high:
- Proceed to: PERMANENT FAULT, SIGNAL TOO HIGH section below.
If Status message is: Permanent fault, signal too low:
- Proceed to: PERMANENT FAULT, SIGNAL TOO LOW section below.
If Status message is: Intermittent fault, signal too high:
- Proceed to: INTERMITTENT FAULT, SIGNAL TOO HIGH section below.
If Status message is: Intermittent fault, signal too low:
- Proceed to: INTERMITTENT FAULT, SIGNAL TOO LOW section below.

PERMANENT FAULT, SIGNAL TOO HIGH





Checking the Ground Lead
^ Switch Ignition OFF.
^ Wait for approx. 150 seconds.
^ Disconnect A/C pressure sensor.
^ Connect an ohmmeter between the A/C pressure sensor's connector 1 and ground.

The ohmmeter should show approx. 0 ohms.

If reading is OK:
- Check the signal lead.
If reading is incorrect:
- Check the ECM connector.





Checking the ECM Connector
^ Switch Ignition OFF.
^ A/C pressure sensor disconnected.
^ Rectify the ECM's connector with regard to contact resistance and oxidation.





^ ECM connected.
^ Connect an ohmmeter between the A/C pressure sensor's connector 1 and ground.

The ohmmeter should show approx. 0 ohms.

If reading is OK:
- Check the signal lead.
If reading is incorrect:
- Check the lead between the A/C pressure sensor connector 1 and ECM B28 for signs of a break.





Checking the Signal Lead
^ Switch Ignition ON.
^ A/C pressure sensor disconnected.
^ Connect a voltmeter between the A/C pressure sensor connector 2 and ground.

The voltmeter should show approx. 5 Volts.

If reading is OK:
- Check the A/C pressure sensor.
If the voltmeter shows approx. 0 Volts:
- Check the ECM connector.
If the voltmeter shows more than approx. 5 Volts:
- Check the lead between the A/C pressure sensor connector 2 and ECM B9 for signs of short circuiting to voltage supply.





Checking the ECM Connector
^ Switch Ignition OFF.
^ A/C pressure sensor disconnected.
^ Rectify the ECM's connector with regard to contact resistance and oxidation.





^ ECM connected.
^ Switch Ignition ON.
^ Connect a voltmeter between A/C pressure sensor connector 2 and ground.

The voltmeter should show approx. 5 Volts.

If reading is OK:
- The cause of the DTC is poor contact in the ECM connector.
If the voltmeter shows approx. 0 Volts:
- Check the lead between A/C pressure sensor connector 2 and the ECM B9 for signs of a break.





Checking the A/C Pressure Sensor
^ Switch Ignition OFF.
^ Connect A/C pressure sensor.
^ START the engine and let it idle for at least 15 seconds.
^ A/C button ON.
^ Blower ON.
^ Look up the DTC parameter list.





^ Read the parameter "A/C APPROVED".

If the parameter shows YES:
- The cause of the DTC is poor contact in the A/C pressure sensor connector.
- Rectify the connector with regard to contact resistance and oxidation.
If the parameter shows NO:
- Test with a new A/C pressure sensor.

PERMANENT FAULT, SIGNAL TOO LOW





Checking the Signal Lead
^ Switch Ignition OFF.
^ Disconnect the A/C pressure sensor.
^ Switch Ignition ON.
^ Connect a voltmeter between the A/C pressure sensor's connector 2 and ground.

The voltmeter should show approx. 5 Volts.

If reading is OK:
- Test with a new A/C pressure sensor.
If reading is incorrect:
- Check the lead between the A/C pressure sensor connector 2 and ECM B9 for signs of short circuiting to ground.

INTERMITTENT FAULT, SIGNAL TOO HIGH





Checking the Leads And Connections
^ Check the A/C pressure sensor's and ECM's connectors for signs of a loose connection as well as contact resistance and oxidation.
^ Check the lead between the A/C pressure sensor connector 1 and ECM B28 for signs of an intermittent break.
^ Check the lead between the A/C pressure sensor connector 2 and ECM B9 for signs of an intermittent break and intermittent short circuiting to voltage supply.

INTERMITTENT FAULT, SIGNAL TOO LOW

Checking the Leads And Connections
^ Check the lead between A/C pressure sensor connector 2 and ECM B9 for signs of intermittent short circuiting to ground.