DTC Troubleshooting

DTC Troubleshooting: P1780

DTC P1780: Shift Control System (Transmission Default Mode)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review General Troubleshooting Information. How To Troubleshoot A/T Systems

1. Clear the DTC with the HDS.

2. Test-drive the vehicle with the shift lever in D, and let the transmission shift through all five gears, then slow down to a stop.

3. Check for Pending or Confirmed DTCs with the HDS.
NOTE: DTC P1780 means there is one or more A/T DTCs about the shift control system.

Are there other DTCs?
YES - Troubleshoot the problem indicated by the DTC.

NO - Go to step 4.


4. Update the A/T software in the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM. Reading and Clearing Diagnostic Trouble Codes

5. Test-drive the vehicle with the shift lever in D, and let the transmission shift through all five gears, then slow down to a stop.

6. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P1780 indicated?
YES - If the PCM was updated, substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the PCM was substituted, go to step 1.

NO - Go to step 7.


7. Monitor the OBD STATUS for P1780 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. Service and Repair If any other Pending or Confirmed DTCs were indicated on step 6, go to the indicated DTC's troubleshooting.

NO - Check for poor connections and loose terminals at the PCM. If the PCM was updated, substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, return to step 5 and recheck.