DTC Troubleshooting: U0104 (126)
DTC U0104:
 F-CAN Malfunction (ECM/PCM-ACC Unit)
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
  1. Turn the ignition switch to ON (II).
  1. Check for Temporary DTCs or DTCs with the HDS.
Are DTC U0029 and U0104 indicated at the same time?
YES -
NO -
Go to Step 3 .
  1. Clear the DTC with the HDS.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC U0104 indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the gauge control module, the ACC unit, and the ECM/PCM.■
  1. Check for communication to the driving support system with the HDS.
Does the HDS communicate with the ACC unit?
YES -
Go to Step 6 .
NO -
  1. Turn the ignition switch to LOCK (0).
  1. Jump the SCS line with the HDS.
  1. Disconnect the ACC unit 20P connector.
  1. Disconnect ECM/PCM connector A (49P).
  1. Connect ACC unit 20P connector terminal No. 10 to body ground with a jumper wire.
  1. Check for continuity between ECM/PCM connector terminal A3 and body ground.
Is there continuity?
YES -
Go to Step 12 .
NO -
Repair open in the wire between the ECM/PCM (A3) and the ACC unit, then go to Step 14 .
  1. Connect ACC unit 20P connector terminal No. 20 to body ground with a jumper wire.
  1. Check for continuity between ECM/PCM connector terminal A4 and body ground.
Is there continuity?
YES -
Substitute a known-good ACC unit, then go to Step 14 and recheck. If DTC U0104 is not indicated, replace the original ACC unit, then go to Step 14 .
NO -
Repair open in the wire between the ECM/PCM (A4) and the ACC unit, then go to Step 14 .
  1. Reconnect all connectors.
  1. Turn the ignition switch to ON (II).
  1. Reset the ECM/PCM with the HDS.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC U0104 indicated?
YES -
Check for poor connections or loose terminals at the gauge control module, the ACC unit, and the ECM/PCM, then go to Step 1 .
NO -
Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.■