A/C Pressure Sensor Circuit

A/c Pressure Sensor Circuit:

WHEN MONITORED
Engine Running with the A/C on.

SET CONDITION
The A/C Heater Control Module detects an abnormally high or low voltage on the A/C Pressure Sensor Signal circuit.

POSSIBLE CAUSES
- A/C pressure sensor signal circuit shorted to battery voltage
- A/C pressure sensor signal circuit shorted to 5-volt supply circuit
- A/C pressure sensor signal circuit shorted to ground
- A/C pressure sensor signal circuit shorted to sensor ground circuit
- A/C pressure sensor 5-volt supply circuit open
- A/C pressure sensor 5-volt supply circuit shorted to ground
- A/C pressure sensor
- A/C pressure sensor signal circuit open
- A/C pressure sensor ground circuit open
- A/C heater control module

Diagnostic Test




1. READ A/C PRESSURE SENSOR VOLTAGE WITH DRB III(R)

NOTE: Ensure the A/C refrigerant system is properly charged to specifications.

Turn the ignition on.
With the DRB III(R), read the A/C Pressure Sensor voltage.

Q: Is the voltage above 4.5 volts?

YES: Go to 2
NO: Go to 7




2. MEASURE THE RESISTANCE FROM THE A/C PRESSURE SENSOR SIGNAL CIRCUIT TO THE 5-VOLT SUPPLY CIRCUIT

Turn the ignition off.
Disconnect the A/C Pressure Sensor harness connector.

NOTE:
- Check connector - Clean/repair as necessary. Disconnect the A/C Heater Control Module harness connector.
- Check connector - Clean/repair as necessary.

Measure the resistance from the A/C Pressure Sensor Signal circuit to the 5-Volt supply circuit at the A/C Pressure Sensor harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Repair the A/C Pressure Sensor Signal circuit for a short to the 5-Volt Supply circuit. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Go to 3




3. MEASURE THE VOLTAGE ON THE A/C PRESSURE SENSOR SIGNAL CIRCUIT

Turn the ignition on.
Measure the voltage on the A/C Pressure Sensor Signal circuit at the A/C Pressure Sensor harness connector.

Q: Is the voltage above 5.2 volts?

YES: Repair the A/C Pressure Sensor Signal circuit for a short to battery voltage. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Go to 4




4. MONITOR A/C PRESSURE SENSOR VOLTAGE WITH DRB III(R)

Turn the ignition off.
Connect a jumper wire between the A/C Pressure Sensor Signal circuit and the Sensor ground circuit.
Turn the ignition on.
With the DRB III(R), monitor the A/C Pressure Sensor voltage.

Q: Is the voltage below 1.0 volt?

YES: Replace the A/C Pressure Sensor. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Go to 5




5. MEASURE THE RESISTANCE OF THE A/C PRESSURE SENSOR SIGNAL CIRCUIT

Turn the ignition off.
Measure the resistance of the A/C Pressure Sensor Signal circuit from the A/C Heater Control Module harness connector to the A/C Pressure Sensor harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Go to 6
NO: Repair the A/C Pressure Sensor Signal circuit for an open. Perform BODY VERIFICATION TEST. Body Verification Test




6. MEASURE THE RESISTANCE BETWEEN GROUND AND THE A/C PRESSURE SENSOR GROUND CIRCUIT

With the ignition off.
Measure the resistance between ground and the A/C Pressure Sensor Ground circuit at the A/C Pressure Sensor harness connector.

Q: Is the resistance below 30 ohms?

YES: Replace the A/C Heater Control Module. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Repair the A/C Pressure Sensor ground circuit for an open. Perform BODY VERIFICATION TEST. Body Verification Test




7. READ A/C PRESSURE SENSOR VOLTAGE WITH DRB III(R)

With the ignition on.
With the DRB III(R), read the A/C Pressure Sensor voltage.

Q: Is the voltage below 0.5 of a volt?

YES: Go to 8
NO: The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition. Perform BODY VERIFICATION TEST. Body Verification Test




8. MEASURE THE VOLTAGE OF THE 5-VOLT SUPPLY CIRCUIT

Turn the ignition off.
Disconnect the A/C Pressure Sensor harness connector.

NOTE: Check connector - Clean/repair as necessary. Turn the ignition on.

Measure the voltage of the 5-Volt Supply circuit at the A/C Pressure Sensor harness connector.

Q: Is the voltage between 4.5 and 5.0 volts?

YES: Go to 9
NO: Go to 12




9. MONITOR A/C PRESSURE SENSOR VOLTAGE WITH DRB III(R)

With the ignition on.
With the DRB III(R), monitor the A/C Pressure Sensor voltage.

Q: Is the voltage above 0.5 of a volt?

YES: Replace the A/C Pressure Sensor. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Go to 10




10. MEASURE THE RESISTANCE BETWEEN GROUND AND THE A/C PRESSURE SENSOR SIGNAL CIRCUIT

Turn the ignition off.
Disconnect the A/C Heater Control Module harness connector.

NOTE: Check connector - Clean/repair as necessary.

Measure the resistance between ground and the A/C Pressure Sensor Signal circuit in the A/C Pressure Sensor harness connector.

Q: Is the resistance below 100 ohms?

YES: Repair the A/C Pressure Sensor Signal circuit for a short to ground. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Go to 11




11. MEASURE THE RESISTANCE FROM THE A/C PRESSURE SENSOR SIGNAL CIRCUIT TO THE SENSOR GROUND CIRCUIT

With the ignition off.
Measure the resistance from the A/C Pressure Sensor Signal circuit to the Sensor Ground circuit at the A/C Pressure Sensor harness connector.

Q: Is the resistance below 100 ohms?

YES: Repair the A/C Pressure Sensor Signal circuit for a short to the Sensor Ground circuit. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Replace the A/C Heater Control Module. Perform BODY VERIFICATION TEST. Body Verification Test




12. MEASURE THE RESISTANCE BETWEEN GROUND AND THE A/C PRESSURE SENSOR 5-VOLT SUPPLY CIRCUIT

Turn the ignition off.
Disconnect the A/C Heater Control Module harness connector.
Measure the resistance between ground and the 5-Volt Supply circuit at the A/C Pressure Sensor harness connector.

Q: Is the resistance below 100 ohms?

YES: Repair the 5-Volt Supply circuit for a short to ground. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Go to 13




13. MEASURE THE RESISTANCE OF THE A/C PRESSURE SENSOR 5-VOLT SUPPLY CIRCUIT

With the ignition off.
Measure the resistance of the 5-Volt Supply circuit from the A/C Pressure Sensor harness connector to the A/C Heater Control Module harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Replace the A/C Heater Control Module. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Repair the A/C Pressure Sensor 5-Volt Supply circuit for an open. Perform BODY VERIFICATION TEST. Body Verification Test