DTC U0104 (2014 2015 PGM-FI System)

DTC U0104  : F-CAN Malfunction (PCM-ACC Unit)

DTC (PGM-FI)

1. DTC check

   -1. Turn the vehicle to the ON mode.

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

   DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
   U0029 F-CAN Malfunction (BUS-OFF (PCM))
   U0104 F-CAN Malfunction (PCM-ACC Unit)

   Are DTC U0029 and U0104 indicated at the same time?

   YES 

   Do the troubleshooting for DTC U0029 - Refer to: DTC Troubleshooting: U0029(PGM-FI System (With CAN Gateway)) (2016),  or DTC Troubleshooting: U0029(PGM-FI System) .

   NO 

   Go to step 2.

2. Problem verification

   -1. Clear the DTC with the HDS.

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

   DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
   U0104 F-CAN Malfunction (PCM-ACC Unit)

   Is DTC U0104 indicated?

   YES 

   The failure is duplicated. Go to step 3.

   NO 

   Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the ACC unit 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.

3. Driving support system check

   -1. Check for communication to the DRIVING SUPPORT system with the HDS.

   Does the HDS communicate with the ACC unit?

   YES 

   Go to step 4.

   NO 

   Refer to the appropriate Procedure in Adaptive Cruise Control (ACC) Symptom Troubleshooting or Lane Keeping Assist System (LKAS) Symptom Troubleshooting . .

4. Open wire check (F-CAN_H line)

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

   - 2. Jump the SCS line with the HDS.

   - 3. Disconnect the following connectors.

   PCM connector A (51P) - Refer to: How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the A/T System (2014 2015), or How to Troubleshoot the Brake Booster Pressure Monitoring System (2014 2015 2016 2017 2018 2019 2020)

   ACC unit 20P connector

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

   Test condition	Vehicle OFF (LOCK) mode
   	PCM connector A (51P): disconnected
   	ACC unit 20P connector: disconnected
   Test circuit	F-CAN_H
   Test point 1	ACC unit 20P connector No. 2 (WHT)
   Test point 2	PCM connector A (51P) No. 9 (WHT)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The F-CAN_H wire is OK. Go to step 5.

   NO 

   Repair an open in the F-CAN_H wire between the PCM (A9) and the ACC unit.

5. Open wire check (F-CAN_L line)

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

   Test condition	Vehicle OFF (LOCK) mode
   	PCM connector A (51P): disconnected
   	ACC unit 20P connector: disconnected
   Test circuit	F-CAN_L
   Test point 1	ACC unit 20P connector No. 13 (BLK)
   Test point 2	PCM connector A (51P) No. 10 (BLK)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The F-CAN_L wire is OK. Update the ACC unit if it does not have the latest software, then recheck. If DTC U0104 is indicated after updated, replace the original ACC unit .

   NO 

   Repair an open in the F-CAN_L wire between the PCM (A10) and the ACC unit.