Possible Causes
WARNING: This page is about a different car, the 2002 Mazda 626 and 2001 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
Following items are possible causes for DTC P1780:
- O/D OFF switch malfunction.
- Open or short to ground in circuits between O/D OFF switch and PCM.
- Damaged connectors or wiring harness between O/D OFF switch and PCM.
- PCM malfunction.