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Home >> Honda >> 2021 >> Pilot Special Edition, AWD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> HVAC System - DTC Diagnostics >> DTC Troubleshooting >> DTC B2973 (7)

DTC B2973 (7)

DTC B2973 or DTC indicator 7  : A Short in the Mode Control Motor B Circuit (Front)

NOTE:

If other short circuit DTCs are indicated at the same time, there may be an open or short to body ground in the power (5 V) circuit.

DTC Description DTC
B2973 A short in the mode control motor B circuit (front)  

DTC (AC)

  1. Problem verification

    - 1. Clear the DTC with the HDS.

    - 2. Turn the vehicle to the OFF (LOCK) mode then the ON mode.

    - 3. Do the Self-Diagnostic Function with the HDS or the HVAC control unit.

    - 4. Wait for at least 8 seconds.

    - 5. Check for DTCs.

    DTC Description DTC
    B2973 A short in the mode control motor B circuit (front)  

    Is DTC B2973 or 7 indicated?

    YES 

    Go to step 2.

    NO 

    Intermittent failure. Check for loose wires or poor connections on the mode control motor B circuit.

  2. Determine possible failure area (SENSOR 5V line, others)

    - 1. Turn the vehicle to the OFF (LOCK) mode.

    - 2. Disconnect the following connector.

    Mode control motor B 7P connector

    - 3. Turn the vehicle to the ON mode.

    - 4. Measure the voltage between test points 1 and 2.

    Test condition Vehicle ON mode
    Mode control motor B 7P connector: disconnected
    Test point 1 Mode control motor B 7P connector No. 1
    Test point 2 Body ground
    GHH310139Courtesy of HONDA, U.S.A., INC.

    Is there about 5 V?

    YES 

    The SENSOR 5V wire is OK. Go to step 3.

    NO 

    Go to step 6.

  3. Mode control motor B check (MOD-P HD line)

    - 1. Measure the voltage between test points 1 and 2.

    Test condition Vehicle ON mode
    Mode control motor B 7P connector: disconnected
    Test point 1 Mode control motor B 7P connector No. 2
    Test point 2 Body ground
    GHH310140Courtesy of HONDA, U.S.A., INC.

    Is there about 5 V?

    YES 

    The MOD-P HD wire is OK. Replace the mode control motor B .

    NO 

    Go to step 4.

  4. Shorted wire check (MOD-P HD line)

    - 1. Turn the vehicle to the OFF (LOCK) mode.

    - 2. Disconnect the following connector.

    HVAC control unit connector C (12P)

    - 3. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
    HVAC control unit connector C (12P): disconnected
    Mode control motor B 7P connector: disconnected
    Test point 1 HVAC control unit connector C (12P) No. 4
    Test point 2 Body ground

    Is there continuity?

    YES 

    Repair a short to body ground in the wire between the HVAC control unit and the mode control motor B.

    NO 

    The MOD-P HD wire is not shorted. Go to step 5.

  5. Shorted wire check (MOD-P HD line to SENSOR(COM) line)

    - 1. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
    HVAC control unit connector C (12P): disconnected
    Mode control motor B 7P connector: disconnected
    Test point 1 Mode control motor B 7P connector No. 2
    Test point 2 Mode control motor B 7P connector No. 3
    GHH310141Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Repair a short in the wires between the HVAC control unit and the mode control motor B.

    NO 

    The MOD-P HD wire to SENSOR(COM) wire are OK. Replace the HVAC control unit .

  6. Open wire check (SENSOR 5V line)

    - 1. Measure the voltage between test points 1 and 2.

    Test condition Vehicle ON mode
    Mode control motor B 7P connector: disconnected
    Test point 1 HVAC control unit connector A (32P) No. 5
    Test point 2 Body ground

    Is there about 5 V?

    YES 

    Repair an open in the wire between the HVAC control unit and the mode control motor B.

    NO 

    The SENSOR 5V wire is not open. Go to step 7.

  7. Shorted wire check (SENSOR 5V line)

    - 1. Turn the vehicle to the OFF (LOCK) mode.

    - 2. Disconnect the following connector.

    HVAC control unit connector A (32P)

    - 3. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
    HVAC control unit connector A (32P): disconnected
    Mode control motor B 7P connector: disconnected
    Test point 1 HVAC control unit connector A (32P) No. 5
    Test point 2 Body ground

    Is there continuity?

    YES 

    Repair a short to body ground in the wire between the HVAC control unit and the mode control motor B.

    NO 

    The SENSOR 5V wire is OK. Replace the HVAC control unit .