U Code Charts

DTC U0101: A/T F1 Signal A/B Malfunction

NOTE: Information marked with double asterisk (**) applies to 2004-2005 CVT models.

1. Reset the ECM with the HDS.
2. Drive the vehicle several minutes until so the transmission upshifts and downshifts several times.
3. Check for Temporary DTCs or DTCs with the HDS.

Is DTC (U0101)** indicated?

YES - Go to step 4.

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the TCM and the ECM.

4. Turn the ignition switch OFF.
5. Disconnect ECM connector C (31P).
6. Disconnect TCM connector B (22P).




7. Check for continuity between body ground and ECM connector terminals C15 and C11.

Is there continuity?

YES - Repair short in the wire between the ECM (C15, C11) and the TCM (B6,B7).

NO - Go to step 8.




8. Check for continuity between ECM connector terminal C15 and TCM connector terminal B7, and between ECM connector terminal C11 and TCM connector terminal B6.

Is there continuity?

YES - Check the these items:

- Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
- Substitute a known-good TCM, and recheck. If the symptom/indication goes away, replace the original TCM.

NO - Repair open in the wire between the ECM (C15, C11) and the TCM (B6, B7).