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Home >> Honda >> 2021 >> CR-V EX-L, AWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 14 (HVAC System - Diagnostics (Hybrid)) >> DTC Troubleshooting >> DTC B123F (A-A3), B123F (17)

DTC B123F (A-A3), B123F (17)

WARNING: This page is about a different variant/trim than selected.

DTC B123F, DTC screen A-A3, or DTC screen 17  : Automatic lighting control unit/sunlight sensor error

NOTE:  Check for DTCs. If a DTC U1280, Error on the DTC screen I-A1 *1, or DTC screen 80 *2 indicated, troubleshoot this DTC first.

*1: Climate control panel without display

*2: Climate control panel with display

DTC Description DTC
B123F Automatic lighting control unit/sunlight sensor error  

DTC (AC)

  1. Problem verification

    -1. Clear the DTCs with the HDS.

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

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

    -4. Check for DTCs.

    DTC Description DTC
    B123F Automatic lighting control unit/sunlight sensor error  

    Is DTC B123F, Error on the DTC screen A-A3 (climate control panel without display), or DTC screen 17 (climate control panel with display) indicated?

    YES 

    The failure is duplicated. Go to step 2.

    NO 

    Intermittent failure, the system is OK at this time.

  2. Equipment check

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

    -2. Confirm the vehicle have an automatic wiper system.

    Does the wiper/washer switch have an AUTO position?

    YES 

    Go to step 3.

    NO 

    Go to step 8.

  3. Open wire check (TSUN line)

    -1. Disconnect the following connectors.

    Climate control unit connector A (32P)
    Sunlight sensor 2P connector

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

    Test condition Vehicle OFF (LOCK) mode
    Climate control unit connector A (32P): disconnected
    Sunlight sensor 2P connector: disconnected
    Test point 1 Climate control unit connector A (32P) No. 10
    Test point 2 Sunlight sensor 2P connector (female terminals) No. 2:
    GHH379442Courtesy of HONDA, U.S.A., INC.

    Is there 1.0 Ω or less?

    YES 

    The TSUN wire is not open. Go to step 4.

    NO 

    Repair an open in the TSUN wire.

  4. Open wire check (SENSOR_COM line)

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

    Test condition Vehicle OFF (LOCK) mode
    Climate control unit connector A (32P): disconnected
    Sunlight sensor 2P connector: disconnected
    Test point 1 Climate control unit connector A (32P) No. 12
    Test point 2 Sunlight sensor 2P connector (female terminals) No. 1:
    GHH379444Courtesy of HONDA, U.S.A., INC.

    Is there 1.0 Ω or less?

    YES 

    The SENSOR_COM wire is OK. Go to step 5.

    NO 

    Repair an open in the SENSOR_COM wire.

  5. Shorted wire check (TSUN line)

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

    Test condition Vehicle OFF (LOCK) mode
    Climate control unit connector A (32P): disconnected
    Sunlight sensor 2P connector: disconnected
    Test point 1 Climate control unit connector A (32P) No. 10
    Test point 2 Body ground

    Is there 1 MΩ or more?

    YES 

    The TSUN wire is not shorted. Go to step 6.

    NO 

    Repair a short to body ground in the TSUN wire.

  6. Shorted wire check (TSUN line to SENSOR_COM line)

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

    Test condition Vehicle OFF (LOCK) mode
    Climate control unit connector A (32P): disconnected
    Sunlight sensor 2P connector: disconnected
    Test point 1 Climate control unit connector A (32P) No. 10
    Test point 2 Climate control unit connector A (32P) No. 12

    Is there 1 MΩ or more?

    YES 

    The TSUN wire and the SENSOR_COM wire are OK. Go to step 7.

    NO 

    Repair a short in the TSUN wire to the SENSOR_COM wire.

  7. Sunlight sensor check

    -1. Reconnect the following connectors.

    Climate control unit connector A (32P)
    Sunlight sensor 2P connector

    -2. Test the sunlight sensor .

    Is the sunlight sensor OK?

    YES 

    Replace the climate control unit .

    NO 

    Replace the sunlight sensor .

  8. Fuse check:NOTE:  Check for DTCs. If a DTC U1280, Error on the DTC screen I-A1 *1, or DTC indicator 80 *2 indicated, troubleshoot the DTC first.-1.

    Check the following fuse.

    Fuse No. A18

    Is the fuse OK?

    YES 

    Go to step 9.

    NO 

    Replace the fuse, and recheck. If the fuse blows again, repair a short in the No. A18 fuse circuit.

  9. Determine possible failure area (B-CAN lines, others)

    -1. Disconnect the following connector.

    Automatic lighting control unit-sensor 5P connector

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

    Test condition Vehicle OFF (LOCK) mode
    Automatic lighting control unit-sensor 5P connector: disconnected
    Test point 1 Automatic lighting control unit-sensor 5P connector No. 3
    Test point 2 Automatic lighting control unit-sensor 5P connector No. 4

    Is there battery voltage?

    YES 

    Go to step 10.

    NO 

    Go to step 13.

  10. Open wire check (B-CAN_H line)

    -1. Disconnect the following connector.

    Climate control unit connector A (32P)

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

    Test condition Vehicle OFF (LOCK) mode
    Automatic lighting control unit-sensor 5P connector: disconnected
    Climate control unit connector A (32P): disconnected
    Test point 1 Automatic lighting control unit-sensor 5P connector No. 1
    Test point 2 Climate control unit connector A (32P) No. 25

    Is there 1.0 Ω or less?

    YES 

    The B-CAN_H wire is OK. Go to step 11.

    NO 

    Repair an open in the B-CAN_H wire.

  11. Open wire check (B-CAN_L line)

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

    Test condition Vehicle OFF (LOCK) mode
    Automatic lighting control unit-sensor 5P connector: disconnected
    Climate control unit connector A (32P): disconnected
    Test point 1 Automatic lighting control unit-sensor 5P connector No. 2
    Test point 2 Climate control unit connector A (32P) No. 8

    Is there 1.0 Ω or less?

    YES 

    The B-CAN_L wire is OK. Go to step 12.

    NO 

    Repair an open in the B-CAN_L wire.

  12. DTC check

    -1. Reconnect the following connectors.

    Automatic lighting control unit-sensor 5P connector
    Climate control unit connector A (32P)

    -2. Clear the DTC with the HDS.

    -3. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

    -4. Wait for at least 8 seconds.

    -5. Do the Self-Diagnostic Function with the climate control unit .

    -6. Check for DTCs.

    DTC Description DTC
    B123F Automatic lighting control unit/sunlight sensor error  
    U128D Climate Control Unit Lost communication with gauge control module  

    Are DTC B123F, Error on the DTC screen A-A3 *1, or DTC screen 17 *2 and DTC U128D, Error on the DTC screen I-A2 *1, or DTC screen 83 *2 indicated?

    YES 

    Replace the climate control unit .

    NO 

    Replace the automatic lighting control unit-sensor .

  13. Open wire check (+B_BACK_UP line)

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

    Test condition Vehicle OFF (LOCK) mode
    Automatic lighting control unit-sensor 5P connector: disconnected
    Test point 1 Automatic lighting control unit-sensor 5P connector No. 4
    Test point 2 Body ground

    Is there battery voltage?

    YES 

    Check for an open in the GND wire between the automatic lighting control unit-sensor and body ground. If the wire is OK, check for poor ground at G402.

    NO 

    Repair an open in the +B_BACK_UP wire.

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