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Home >> Acura >> 2014 >> MDX SH-AWD >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transaxle - DTC Diagnostics (2 Of 2) (Except Hybrid) >> DTC Troubleshooting >> DTC U0122 (A/T System (With CAN Gateway)) (2016 2017 2018)

DTC U0122 (A/T System (With CAN Gateway)) (2016 2017 2018)

DTC U0122  : Lost Communication With VSA Modulator-Control Unit

NOTE:

  • Before you troubleshoot, record all freeze data and any on-board snapshots, and review the General Troubleshooting Information .
  • According to the detected DTC (s), check for the power circuit and the ground circuit of the control unit which cannot communicate with the TCM.

DTC Description Confirmed DTC Pending DTC Freeze Frame
U0122 Lost Communication With VSA Modulator-Control Unit      

DTC (A/T)

  1. Problem verification

    - 1. Turn the vehicle to the ON mode.

    - 2. Clear the DTC with the HDS.

    - 3. Check for Pending or Confirmed DTCs with the HDS.

    DTC Description Confirmed DTC Pending DTC Freeze Frame
    U0122 Lost Communication With VSA Modulator-Control Unit      

    Is DTC U0122 indicated?

    YES 

    The failure is duplicated. Go to step 2.

    NO 

    Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the VSA modulator-control unit, the CAN gateway, and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.

  2. CAN gateway system DTC check

    - 1. Turn the vehicle to the ON mode.

    - 2. Check for CAN gateway system DTCs with the HDS.

    DTC Description DTC
    U0029-00 CAN Gateway F-CAN ch A Bus Off  
    U0047-00 CAN Gateway F-CAN ch B Bus Off  
    U3000-49 CAN Gateway Internal Failure  

    Is DTC U0029-00, U0047-00, and/or U3000-49 indicated?

    YES 

    Go to the indicated DTC's troubleshooting in the CAN gateway system .

    NO 

    Go to step 3.

  3. F-CAN circuit communication check

    - 1. Select the FUNCTION TEST in the CAN gateway with the HDS, then select the F-CAN Bus Connected Unit Check.

    F-CAN Bus Connected Unit Check

    Which result is indicated?

    TCM (Bus A) is Not Available

    Go to step 4.

    TCM (Bus B) is Not Available

    Go to step 6.

    VSA MODULATOR-CONTROL UNIT (Bus A) is Not Available

    Go to step 8.

    VSA MODULATOR-CONTROL UNIT (Bus B) is Not Available

    Go to step 10.

    TCM and VSA MODULATOR-CONTROL UNIT are Detected

    Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals between the VSA modulator-control unit, the CAN gateway, and the TCM.

  4. Open wire check (F-CAN A_H line)

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

    - 2. Disconnect the following connectors.

    CAN gateway 24P connector
    TCM 58P connector

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

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      TCM 58P connector: disconnected
    Test point 1 CAN gateway 24P connector No. 14
    Test point 2 TCM 58P connector No. 34
    GHH316232Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN A_H wire is OK. Go to step 5.

    NO 

    Repair an open in the F-CAN A_H wire between the CAN gateway and the TCM.

  5. Open wire check (F-CAN A_L line)

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

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      TCM 58P connector: disconnected
    Test point 1 CAN gateway 24P connector No. 15
    Test point 2 TCM 58P connector No. 47
    GHH316233Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN A_L wire is OK. Update the TCM if it does not have the latest software , or substitute a known-good TCM , then recheck. If this DTC goes away and the TCM was updated, troubleshooting is complete. If this DTC goes away and the TCM was substituted, replace the original TCM .

    NO 

    Repair an open in the F-CAN A_L wire between the CAN gateway and the TCM.

  6. Open wire check (F-CAN B_H line)

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

    - 2. Disconnect the following connectors.

    CAN gateway 24P connector
    TCM 58P connector

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

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      TCM 58P connector: disconnected
    Test point 1 CAN gateway 24P connector No. 11
    Test point 2 TCM 58P connector No. 7
    GHH316234Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN B_H wire is OK. Go to step 7.

    NO 

    Repair an open in the F-CAN B_H wire between the CAN gateway and the TCM.

  7. Open wire check (F-CAN B_L line)

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

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      TCM 58P connector: disconnected
    Test point 1 CAN gateway 24P connector No. 10
    Test point 2 TCM 58P connector No. 20
    GHH316235Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN B_L wire is OK. Update the TCM if it does not have the latest software , or substitute a known-good TCM , then recheck. If this DTC goes away and the TCM was updated, troubleshooting is complete. If this DTC goes away and the TCM was substituted, replace the original TCM .

    NO 

    Repair an open in the F-CAN B_L wire between the CAN gateway and the TCM.

  8. Open wire check (F-CAN A_H line)

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

    - 2. Disconnect the following connectors.

    CAN gateway 24P connector
    VSA modulator-control unit 38P connector

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

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      VSA modulator-control unit 38P connector: disconnected
    Test point 1 CAN gateway 24P connector No. 14
    Test point 2 VSA modulator-control unit 38P connector No. 38 - Refer to:
    VSA Modulator-Control Unit Connector for Inputs and Outputs (2016), or
    VSA Modulator-Control Unit Connector for Inputs and Outputs (2017 2018 2019 2020)
    GHH316236Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN A_H wire is OK. Go to step 9.

    NO 

    Repair an open in the F-CAN A_H wire between the CAN gateway and the VSA modulator-control unit.

  9. Open wire check (F-CAN A_L line)

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

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      VSA modulator-control unit 38P connector: disconnected
    Test point 1 CAN gateway 24P connector No. 15
    Test point 2 VSA modulator-control unit 38P connector No. 26 - Refer to:
    VSA Modulator-Control Unit Connector for Inputs and Outputs (2016), or
    VSA Modulator-Control Unit Connector for Inputs and Outputs (2017 2018 2019 2020)
    GHH316237Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN A_L wire is OK. Update the VSA modulator-control unit if it does not have the latest software , then recheck. If this DTC goes away and the VSA modulator-control unit was updated, troubleshooting is complete. If this DTC is indicated after the VSA modulator-control unit was updated, replace the VSA modulator-control unit .

    NO 

    Repair an open in the F-CAN A_L wire between the CAN gateway and the VSA modulator-control unit.

  10. Open wire check (F-CAN B_H line)

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

    - 2. Disconnect the following connectors.

    CAN gateway 24P connector
    VSA modulator-control unit 38P connector

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

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      VSA modulator-control unit 38P connector: disconnected
    Test point 1 CAN gateway 24P connector No. 11
    Test point 2 VSA modulator-control unit 38P connector No. 31 - Refer to:
    VSA Modulator-Control Unit Connector for Inputs and Outputs (2016), or
    VSA Modulator-Control Unit Connector for Inputs and Outputs (2017 2018 2019 2020)
    GHH316238Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN B_H wire is OK. Go to step 11.

    NO 

    Repair an open in the F-CAN B_H wire between the CAN gateway and the VSA modulator-control unit.

  11. Open wire check (F-CAN B_L line)

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

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      VSA modulator-control unit 38P connector: disconnected
    Test point 1 CAN gateway 24P connector No. 10
    Test point 2 VSA modulator-control unit 38P connector No. 20 - Refer to:
    VSA Modulator-Control Unit Connector for Inputs and Outputs (2017 2018 2019 2020), or
    VSA Modulator-Control Unit Connector for Inputs and Outputs (2016)
    GHH316239Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN B_L wire is OK. Update the VSA modulator-control unit if it does not have the latest software , then recheck. If this DTC goes away and the VSA modulator-control unit was updated, troubleshooting is complete. If this DTC is indicated after the VSA modulator-control unit was updated, replace the VSA modulator-control unit .

    NO 

    Repair an open in the F-CAN B_L wire between the CAN gateway and the VSA modulator-control unit.

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