HVAC

DTC Troubleshooting: B2979 (6)

DTC B2979 or DTC indicator 6:

An Open in the A/C Pressure Sensor Circuit

1. Clear the DTCs with the HDS.

2. Turn the ignition switch to LOCK (0) and then back to ON (II).

3. Do the self-diagnostic function with the HDS or the HVAC control unit.

4. Check for DTCs.

Is DTC B2979 or 6 indicated?

YES -

Go to step 5.

NO -

Intermittent failure, check for loose wires or poor connections in the A/C pressure sensor circuit.�

5. Turn the ignition switch to LOCK (0).

6. Disconnect the A/C pressure sensor 3P connector.

7. Disconnect HVAC control unit connector A (24P).

8. Check for continuity between the following terminals of HVAC control unit connector A (24P) and the A/C pressure sensor 3P connector.









Is there continuity?

YES -

Go to step 9.

NO -

Repair an open in the wire(s) between the HVAC control unit and the A/C pressure sensor.�

9. Reconnect HVAC control unit connector A (24P).

10. Turn the ignition switch to ON (II).

11. Measure the voltage between HVAC control unit connector A (24P) terminals No. 4 and No. 14, and between HVAC control unit connector A (24P) terminals No. 4 and No. 20.





Is there about 5 V?

YES -

Replace the A/C pressure sensor.�

NO -

Check for loose wires or poor connections at HVAC control unit connector A (24P) and at the A/C pressure sensor 3P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/indication goes away, replace the original HVAC control unit HVAC Control Unit Removal/Installation.�