DTC B2980 or DTC indicator B and WINDSHIELD DEFROST: A Short in the A/C Pressure Sensor Circuit

WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

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 SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS ).
Check for DTCs.
Is DTC B2980 or B and WINDSHIELD DEFROST Indicated?

YES -Go to step 5.

NO -Intermittent failure.
Check for DTCs.
Are these DTCs also present; B1234 or K and AUTO, and/or B1237 or N and AUTO, and/or B1245 or G, and/or B2968 or A and WINDSHIELD DEFROST?

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 (40P).
Check for continuity between body ground and climate control unit connector A (40P) terminal No. 26.

Fig 1: Checking For Continuity Between Body Ground And Climate Control Unit Connector A (40P) Terminal No. 26
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 (40P) terminals No. 6 and No. 26.

Fig 2: Checking For Continuity Between Climate Control Unit Connector A (40P) Terminals No. 6 And No. 26
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short in the wires.

NO -Go to step 11.
Turn the ignition switch to ON (II), and measure the voltage between body ground and climate control unit connector A (40P) terminal No. 26.

Fig 3: Measuring Voltage Between Body Ground And Climate Control Unit Connector A (40P) Terminal No. 26
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 (40P).
Turn the ignition switch to ON (II).
Measure the voltage between climate control unit connector A (40P) terminals No. 6 and No. 8, and between climate control unit connector A (40P) terminals No. 8 and No. 26.

Fig 4: Measuring Voltage Between Climate Control Unit Connector A (40P) Terminals No. 6 And No. 8
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 (40P) 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 (40P).
Disconnect these items:
- Driver's air mix control motor
- Passenger's air mix control motor
- Rear air mix control motor
- Humidity/in-car temperature sensor
- A/C pressure sensor
Check for continuity between climate control unit connector A (40P) terminal No. 6 and body ground.

Fig 5: Checking For Continuity Between Climate Control Unit Connector A (40P) Terminal No. 6 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.

Fig 6: Measuring Voltage Between Same Terminal And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

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 (40P).
Turn the ignition switch to ON (II), and measure the voltage between climate control unit connector A (40P) terminal No. 6 and body ground.

Fig 7: Measuring Voltage Between Climate Control Unit Connector A (40P) Terminal No. 6 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 (40P). 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 as described in step 22, reconnect these items individually and note the voltage reading each time:
- Driver's air mix control motor
- Passenger's air mix control motor
- Rear air mix control motor
- Humidity/in-car temperature sensor
- A/C pressure sensor
  
  Fig 8: Measuring Voltage Between Climate Control Unit Connector A (40P) Terminal No. 6 And Body Ground
  Courtesy of AMERICAN HONDA MOTOR CO., INC.
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 CLIMATE CONTROL UNIT REMOVAL/INSTALLATION ).

NO -Replace the component that caused the voltage drop.