Automatic Transmission

DTC U0028: F-CAN Communication Circuit Error (F-CAN Bus OFF)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review General Troubleshooting Information.

1. Clear the DTC with the HDS.
2. Turn the ignition switch to ON (II).
3. Check whether DTC U0028 is indicated in the DTCs/Freeze Data in PGM-FI Mode Menu with the HDS.

Is DTC U0028 indicated in the PGM-FI system?

YES - Troubleshoot for DTC U0028 in the PGM-FI System.

NO - Go to step 4.

4. Check whether DTC U0028 is indicated in the DTCs/Freeze Data in A/T Mode Menu with the HDS.

Is DTC U0028 indicated?

YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time.

5. Update the A/T software in the PCM if it does not have the latest software, or substitute a known-good PCM.
6. Start the engine, and let it idle for 2 minutes.
7. Check for DTC(s) in the DTCs/Freeze Data in A/T Mode Menu with the HDS.

Is DTC U0028 indicated?

YES - If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to step 1.

NO - Go to step 8.

8. Monitor the OBD STATUS for U0028 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.

Does the HDS indicate PASSED?

YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. If any other DTCs were indicated on step 7, go to the indicated DTC's troubleshooting.

NO - Check for poor connections and loose terminals at the PCM and the connectors on the F-CAN circuit. If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, return to step 6 and recheck.