DTC B2980 or DTC indicator M and AUTO: A Short 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 climate control unit (see HOW TO USE THE CLIMATE CONTROL UNIT SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS ).
- Check for DTCs.
Is DTC B2980 or M and AUTO indicated?
YES -Go to step 5.
NO -Intermittent failure. Check for loose wires or poor connections on the A/C pressure sensor circuit.
- Check for DTCs.
Are these DTCs also present; B121D or A and WINDSHIELD DEFROST, and/or B1234 or C and WINDSHIELD DEFROST, and/or B1237 or F and WINDSHIELD DEFROST, and/or B2968 or P and AUTO?
YES -Go to step 16.
NO -Go to step 6.
- Turn the ignition switch to LOCK (0).
- Disconnect the A/C pressure sensor 3P connector.
- Disconnect climate control unit connector A (28P).
- Check for continuity between body ground and climate control unit connector A (28P) terminal No. 23.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Repair a short to body ground in the wire between the climate control unit and the A/C pressure sensor.
NO -Go to step 10.
- Check for continuity between climate control unit connector A (28P) terminals No. 23 and No. 25.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Repair short in the wires.
NO -Go to step 11.
- Turn the ignition switch to ON (II), and measure the voltage between climate control unit connector A (28P) terminal No. 23 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there any voltage?
YES -Repair a short to power in the wire between the climate control unit and the A/C pressure sensor. This short may also damage the climate control unit. Repair a short to power before replacing the climate control unit.
NO -Go to step 12.
- Turn the ignition switch to LOCK (0).
- Reconnect climate control unit connector A (28P).
- Turn the ignition switch to ON (II).
- Measure the voltage between climate control unit connector A (28P) terminals No. 13 and No. 23, and climate control unit connector A (28P) terminals No. 13 and No. 25.Fig 4: Measuring Voltage Between Climate Control Unit Terminals And Climate Control Unit Connector Terminals
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 climate control unit connector A (28P) and at the A/C pressure sensor 3P connector. If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit (see CLIMATE CONTROL UNIT REMOVAL/INSTALLATION ).
- Turn the ignition switch to LOCK (0), and disconnect climate control unit connector A (28P).
- Disconnect these items:
- Driver's air mix control motor
- Passenger's air mix control motor
- Humidity/in-car temperature sensor
- A/C pressure sensor
- Check for continuity between climate control unit connector A (28P) terminal No. 25 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Repair a short to body ground in the wire.
NO -Go to step 19.
- Turn the ignition switch to ON (II), and measure the voltage between the same terminal and body ground.
Is there any voltage?
YES -Repair a short to power in the wire. This short may have also damaged the climate control unit. Repair a short to power before replacing the climate control unit.
NO -Go to step 20.
- Turn the ignition switch to LOCK (0).
- Reconnect climate control unit connector A (28P).
- Turn the ignition switch to ON (II), and measure the voltage between climate control unit connector A (28P) terminal No. 25 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 5 V?
YES -Go to step 23.
NO -Check for a loose wire or poor connection at climate control unit connector A (28P). If the connection is good, substitute a known-good climate control unit and recheck. If the symptom/indication goes away, replace the original climate control unit (see CLIMATE CONTROL UNIT REMOVAL/INSTALLATION ).
- While measuring the voltage between the same terminal and body ground, reconnect these items individually and note the voltage reading each time:
- Driver's air mix control motor
- Passenger's air mix control motor
- Humidity/in-car temperature sensor
- A/C pressure sensor
Does the voltage remain at about 5 V?
YES -Substitute a known-good climate control unit and recheck. If the symptom/indication goes away, replace the original climate control unit (see HVAC CONTROL UNIT INPUTS AND OUTPUTS ).
NO -Replace the component that caused the voltage drop.