Inspection Procedure 34

A/C Pressure Sensor System

A/C Pressure Sensor Circuit Part 1:

A/C Pressure Sensor Circuit Part 2:

CIRCUIT OPERATION
- A 5-volt voltage is supplied to the A/C pressure sensor power terminal (terminal No. 3) from the ECM or the PCM (terminal No. 97). The ground terminal (terminal No. 1) is grounded with the ECM or the PCM (terminal No. 96).
- A voltage that is proportional to the A/C refrigerant pressure is sent from the A/C pressure sensor output terminal (terminal No. 2) to the ECM or the PCM (terminal No. 118).

TECHNICAL DESCRIPTION
- The A/C pressure sensor detects the A/C refrigerant pressure and inputs it into the ECM or the PCM .
- The ECM or the PCM uses this signal for fuel injection mode control.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- A/C pressure sensor failed.
- Open or shorted A/C pressure sensor circuit, or connector damage.
- ECM failed.
- PCM failed.

DIAGNOSIS

STEP 1. Measure the sensor output voltage at A/C pressure sensor connector A-02 by backprobing.

1. Do not disconnect the connector A-02.
2. Start the engine and run at idle.
3. Turn the A/C switch to the "ON" position.
4. Measure the voltage between terminal No. 2 and ground by backprobing.
- When A/C refrigerant pressure is 1 kPa, voltage should be between 1.8 and 2.0 volts.
- When A/C refrigerant pressure is 2 kPa, voltage should be between 3.23 and 3.57 volts.

5. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage within the specified range?

YES: Go to Step 12.

NO: Go to Step 2.

STEP 2. Measure the sensor supply voltage at A/C pressure sensor connector A-02 by backprobing.

1. Do not disconnect the connector A-02.
2. Turn the ignition switch to the "ON" position.

3. Measure the voltage between terminal No. 3 and ground by backprobing.
- Voltage should be between 4.9 and 5.1 volts.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage between 4.9 and 5.1 volts?

YES: Go to Step 7.

NO: Go to Step 3.

STEP 3. Measure the sensor supply voltage at ECM or PCM connector C-112 by backprobing.

1. Do not disconnect the connector C-112.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 97 and ground by backprobing.
- Voltage should be between 4.9 and 5.1 volts.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage between 4.9 and 5.1 volts?

YES: Go to Step 6.

NO: Go to Step 4.

STEP 4. Check harness connector C-112 at ECM or PCM and harness connector A-02 at A/C pressure sensor for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 5.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.

STEP 5. Check for short circuit to ground between A/C pressure sensor connector A-02 (terminal No. 3) and ECM or PCM connector C-112 (terminal No. 97).

NOTE: Check harness after checking intermediate connector A-14. If intermediate connectors are damaged, repair or replace them. Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.

Q: Is the harness wire in good condition?

YES: Replace the ECM or the PCM. Then confirm that the malfunction symptom is eliminated.

NO: Repair it. Then confirm that the malfunction symptom is eliminated.

STEP 6. Check harness connector C-112 at ECM or PCM and harness connector A-02 at A/C pressure sensor for damage.

Q: Is the harness connector in good condition?

YES: Check the connector A-14 at intermediate connector for damage, and repair or replace as required. Refer to Harness Connector Inspection. If intermediate connector is in good condition, repair harness wire between A/C pressure sensor connector A-02 (terminal No. 3) and ECM or PCM connector C-112 (terminal No. 97) because of open circuit and harness damage. Then confirm that the malfunction symptom is eliminated.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.

STEP 7. Measure the ground voltage at A/C pressure sensor connector A-02 by backprobing.

1. Do not disconnect the connector A-02.
2. Turn the ignition switch to the "ON" position.

3. Measure the voltage between terminal No. 1 and ground by backprobing.
- Voltage should be 0.5 volt or less.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage 0.5 volt or less?

YES: Go to Step 10.

NO: Go to Step 8.