Automatic Transmission

DTC U0121: F-CAN Malfunction (PCM-ABS)

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

1. Turn the ignition switch to ON (II).
2. Clear the DTC with the HDS.
3. Check for Temporary DTCs or DTCs in the PGM-FI SYSTEM with the HDS.

Is DTC U0155 indicated in the PGM-FI SYSTEM?

YES - Go to the DTC U0155 troubleshooting in the PGM-FI system.

NO - Go to step 4.

4. Check for DTCs in the A/T SYSTEM with the HDS.

Is DTC U0121 indicated in the A/T SYSTEM?

YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time. If any other DTCs were indicated, go to the indicated DTC's troubleshooting.

5. Update the PCM if it does not have the latest software, or substitute a known good PCM.
6. Start the engine, and wait for at least 2 minutes.
7. Check for DTCs in the A/T SYSTEM with the HDS.

Is DTC U0121 indicated in the A/T SYSTEM?

YES - Check for poor connections or loose terminals at the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 6. If the PCM was substituted, go to step 1.

NO - Go to step 8.

8. Monitor the OBD STATUS for U0121 in the DTCs MENU with the HDS.

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 in step 7, go to the indicated DTC's troubleshooting.

NO - If the HDS indicates FAILED, check for poor connections or loose terminals at the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 6. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 6.