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Home >> Acura >> 2018 >> RLX Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTC Diagnostics (6 Of 6) (Except Hybrid) >> DTC Troubleshooting >> DTC U0122

DTC U0122

DTC U0122  : F-CAN Malfunction (PCM - VSA Modulator-Control Unit)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information .
DTC Description Confirmed DTC Pending DTC Freeze Frame
U0122 F-CAN Malfunction (PCM - VSA Modulator-Control Unit)      

DTC (PGM-FI)

  1. 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  
    U0056-00 CAN Gateway F-CAN ch C Bus Off  
    U3000-49 CAN Gateway Internal Failure  

    Is DTC U0029-00, U0047-00, U0056-00, and/or U3000-49 indicated?

    YES 

    Go to the troubleshooting for CAN gateway system DTC(s) .

    NO 

    Go to step 2.

  2. 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?

    PCM (Bus A) is Not Available

    Go to step 3.

    PCM (Bus B) is Not Available

    Go to step 5.

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

    Go to step 7.

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

    Go to step 9.

    PCM and VSA MODULATOR-CONTROL UNIT are Detected

    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.

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

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

    -2. Jump the SCS line with the HDS.

    -3. Disconnect the following connectors.

    CAN gateway 24P connector
    PCM connector A (51P)

    -4. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      PCM connector A (51P): disconnected
    Test circuit F-CAN A_H
    Test point 1 CAN gateway 24P connector No. 14 (BLU)
    Test point 2 PCM connector A (51P) No. 9 (BLU)
    GHH345377Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN A_H wire is OK. Go to step 4.

    NO 

    Repair an open in the F-CAN A_H wire between the PCM (A9) and the CAN gateway.

  4. 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
      PCM connector A (51P): disconnected
    Test circuit F-CAN A_L
    Test point 1 CAN gateway 24P connector No. 15 (PNK)
    Test point 2 PCM connector A (51P) No. 10 (PNK)
    GHH345378Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN A_L wire is OK. Check for poor connections or loose terminals at the CAN gateway and the PCM. Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If DTC U0122 goes away and the PCM was updated, troubleshooting is complete. If DTC U0122 goes away and the PCM was substituted, replace the original PCM .

    NO 

    Repair an open in the F-CAN A_L wire between the PCM (A10) and the CAN gateway.

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

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

    -2. Jump the SCS line with the HDS.

    -3. Disconnect the following connectors.

    CAN gateway 24P connector
    PCM connector A (51P)

    -4. Check for continuity between test points 1 and 2.

    Test condition Vehicle OFF (LOCK) mode
      CAN gateway 24P connector: disconnected
      PCM connector A (51P): disconnected
    Test circuit F-CAN B_H
    Test point 1 CAN gateway 24P connector No. 11 (LT BLU)
    Test point 2 PCM connector A (51P) No. 11 (LT BLU)
    GHH345379Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Go to step 6.

    NO 

    Repair an open in the F-CAN B_H wire between the PCM (A11) and the CAN gateway.

  6. 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
      PCM connector A (51P): disconnected
    Test circuit F-CAN B_L
    Test point 1 CAN gateway 24P connector No. 10 (GRY)
    Test point 2 PCM connector A (51P) No. 12 (GRY)
    GHH345380Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN B_L wire is OK. Check for poor connections or loose terminals at the CAN gateway and the PCM. Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If DTC U0122 goes away and the PCM was updated, troubleshooting is complete. If DTC U0122 is not indicated the PCM was substituted, replace the original PCM .

    NO 

    Repair an open in the F-CAN B_L wire between the PCM (A12) and the CAN gateway.

  7. 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 circuit F-CAN B_H
    Test point 1 CAN gateway 24P connector No. 11 (LT BLU)
    Test point 2 VSA modulator-control unit 38P connector No. 38 (LT BLU)
    GHH345381Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN B_H wire is OK. Go to step 8.

    NO 

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

  8. 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 circuit F-CAN B_L
    Test point 1 CAN gateway 24P connector No. 10 (GRY)
    Test point 2 VSA modulator-control unit 38P connector No. 26 (GRY)
    GHH345382Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN B_L wire is OK. Check for poor connections or loose terminals at the CAN gateway and the VSA modulator-control unit. Update the VSA modulator-control unit if it does not have the latest software, then recheck. If DTC U0122 goes away and the VSA modulator-control unit was updated, troubleshooting is complete. If DTC U0122 is indicated after the VSA modulator-control unit updated, replace the original 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.

  9. Open wire check (F-CAN C_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 circuit F-CAN C_H
    Test point 1 CAN gateway 24P connector No. 9 (PUR)
    Test point 2 VSA modulator-control unit 38P connector No. 31 (PUR)
    GHH345383Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN C_H wire is OK. Go to step 10.

    NO 

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

  10. Open wire check (F-CAN C_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 circuit F-CAN C_L
    Test point 1 CAN gateway 24P connector No. 8 (PNK)
    Test point 2 VSA modulator-control unit 38P connector No. 20 (PNK)
    GHH345384Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The F-CAN C_L wire is OK. Check for poor connections or loose terminals at the CAN gateway and the VSA modulator-control unit. Update the VSA modulator-control unit if it does not have the latest software, then recheck. If DTC U0122 goes away and the VSA modulator-control unit was updated, troubleshooting is complete. If DTC U0122 is indicated after the VSA modulator-control unit updated, replace the original VSA modulator-control unit .

    NO 

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

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