What does code P1780 mean?

P1780 · MazdaTransmission Control Switch Circuit, Overdrive Off Switch Not Cycled During The Self Test

P1780 on Mazda vehicles indicates that the transmission control module (TCM) did not detect the overdrive off switch being cycled during its self-test routine. The TCM expects to see the switch input change state when the ignition is turned on and the switch is pressed, but it did not receive that signal, so it flags the circuit as faulty.

SystemPowertrain

Code typeMazda specific

SeverityLow

Fix difficultyIntermediate

AreaTransmission

Guidance is general and written for Mazda vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.