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

1.
DTC check:

DTC check
?1.
Press the engine start/stop button to select 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
     
     
     
     
NO
     
     
     
Go to step 2.
2.
Problem verification:

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.?
3.
ACC system check:

ACC system check
?1.
Check for communication to the ACC system with the HDS.

Does the HDS communicate with the ACC unit?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
4.
Open wire check (F CAN-H line):

Open wire check (F CAN-H line)
?1.
Press the engine start/stop button to select the OFF mode.

?2.
Jump the SCS line with the HDS.


?3.
Disconnect the following connectors.

?4.
Check for continuity between test points 1 and 2.
Test condition
OFF 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)


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, then do the repair verification.
5.
Open wire check (F CAN-L line):

Open wire check (F CAN-L line)
?1.
Check for continuity between test points 1 and 2.
Test condition
OFF 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 (RED)
Test point 2
PCM connector A (51P) No. 10 (RED)


Is there continuity?

     
YES
     
     
     
The F CAN-L wire is OK. Update the ACC unit if it does not have the latest software, then do the repair verification. If DTC U0104 is indicated after updated, replace the original ACC unit, then do the repair verification.
     
NO
     
     
     
Repair an open in the F CAN-L wire between the PCM (A10) and the ACC unit, then do the repair verification.
Repair verification:

?1.
Reconnect all connectors.

?2.
Exit the SCS mode with the HDS.


?3.
Press the engine start/stop button to select the ON mode.

?4.
Reset the PCM with the HDS.


?5.
Do the PCM idle learn procedure.

?6.
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
     
     
     
Check for poor connections or loose terminals at the ACC unit and the PCM, then go to step 1.
     
NO
     
     
     
Troubleshooting is complete. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.?