DTC B2979 or DTC indicator 5: An Open in the A/C Pressure Sensor Circuit
- Clear the DTCs with the HDS.
- Turn the ignition switch to LOCK (0), and then back to ON (II).
- Do the Self-Diagnostic Function with the HDS (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITH THE HDS ) or the HVAC control unit (see HOW TO USE THE HVAC CONTROL UNIT SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS ).
- Check for DTCs.
Is DTC B2979 or 5 indicated?
YES -Go to step 5.
NO -Intermittent failure. Check for loose wires or poor connections on the A/C pressure sensor circuit.
- Turn the ignition switch to LOCK (0).
- Disconnect the A/C pressure sensor 3P connector.
- Disconnect the HVAC control unit 28P connector.
- Check for continuity between the following terminals of the HVAC control unit 28P connector and the A/C pressure sensor 3P connector.CONNECTOR TERMINAL REFERENCE CHART
28P: 3P: No. 13 No. 1 No. 23 No. 2 No. 25 No. 3 Fig 1: Checking Continuity Between HVAC Control Unit 28P Connector And A/C Pressure Sensor 3P Connector TerminalsCourtesy of AMERICAN HONDA MOTOR CO., INC.
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.
- Reconnect the HVAC control unit 28P connector.
- Turn the ignition switch to ON (II).
- Measure the voltage between HVAC control unit 28P connector terminals No. 13 and No. 23, and between HVAC control unit 28P connector terminals No. 13 and No. 25.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 5 V?
YES -Replace the A/C pressure sensor.
NO -Check for loose wires or poor connections at the HVAC control unit 28P connector 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 (see HVAC CONTROL UNIT REMOVAL/INSTALLATION ).