P1780

P1780 SHIFT CHANGE SIGNAL

Description

NOTE: If DTC P1780 is displayed with DTC U1000, first perform the trouble diagnosis for DTC U1000. Refer to "DTC U1000 CAN COMMUNICATION LINE".

ECM receives current gear position signal, next gear position signal, shift change signal, shift pattern signal through CAN communication line from TCM (Transmission control module). ECM uses these four signals for engine control.

On Board Diagnosis Logic
Malfunction is detected when
(Malfunction A) The next gear position signal and the current gear position signal are not in the normal pattern compared with the shift pattern signal,
(Malfunction B) The next gear position signal and the current gear position signal are different even through the shift change signal is "OFF".

Possible Cause
- Harness or connectors
(CAN communication line circuit is open or shorted)
- TCM
- A/T unit assembly

DTC Confirmation Procedure

CAUTION: Always drive vehicle at a safe speed.

NOTE: If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 10 seconds before conducting the next test.

With CONSULT-II
1. Perform DTC confirmation procedure for DTC P1754 "DTC Confirmation Procedure".
2. If 1st trip DTC is detected, go to "Diagnostic Procedure".

With GST
Follow the procedure "WITH CONSULT-II" above.

Step 1 - 2:

Step 3:

Diagnostic Procedure