DTC U0122 (2016 2017 2018 PGM-FI System) (With CAN Gateway)

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

NOTE: Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Brake Booster Pressure Monitoring System (2016 2017 2018 2019 2020), or How to Troubleshoot the Fuel and Emissions Systems(With Auto Idle Stop System) (2016), or How to Troubleshoot the Fuel and Emissions Systems .
• According to the detected DTC(s), check for the power circuit and the ground circuit of the control unit which cannot communicate with the PCM.

DTC (PGM-FI)

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 F-CAN Malfunction (PCM-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 troubleshooting for CAN gateway system DTC(s) .

   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?

   PCM (Bus A) is Not Available

   Go to step 4.

   PCM (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.

4. 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 point 1	CAN gateway 24P connector No. 14
   Test point 2	PCM connector A (51P) No. 9 - Refer to: PCM Connector for Inputs and Outputs (2016), or PCM Connector for Inputs and Outputs (2017 2018 2019 2020)

   Courtesy 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 PCM (A9) and the CAN gateway.

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

   	PCM connector A (51P): disconnected
   Test point 1	CAN gateway 24P connector No. 15
   Test point 2	PCM connector A (51P) No. 10 - Refer to: PCM Connector for Inputs and Outputs (2016), or PCM Connector for Inputs and Outputs (2017 2018 2019 2020)

   Courtesy 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 - Refer to: PCM Removal and Installation (2016 2017 2018 2019 2020) , 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 - Refer to: PCM Removal and Installation (2016 2017 2018 2019 2020) .

   NO 

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

6. 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 point 1	CAN gateway 24P connector No. 11
   Test point 2	PCM connector A (51P) No. 11 - Refer to: PCM Connector for Inputs and Outputs (2016), or PCM Connector for Inputs and Outputs (2017 2018 2019 2020)

   Courtesy 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 PCM (A11) and the CAN gateway.

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
   	PCM connector A (51P): disconnected
   Test point 1	CAN gateway 24P connector No. 10
   Test point 2	PCM connector A (51P) No. 12 - Refer to: PCM Connector for Inputs and Outputs (2017 2018 2019 2020), or PCM Connector for Inputs and Outputs (2016)

   Courtesy 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 - Refer to: PCM Removal and Installation (2016 2017 2018 2019 2020) , 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 - Refer to: PCM Removal and Installation (2016 2017 2018 2019 2020) .

   NO 

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

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)

   Courtesy 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 (2017 2018 2019 2020), or VSA Modulator-Control Unit Connector for Inputs and Outputs (2016)

   Courtesy 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 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 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)

    Courtesy 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)

    Courtesy 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 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.