What does code P278D mean?

Q: What does code P278D mean?

Kick Down Switch Circuit High. P278D means the transmission control module (TCM) has detected an abnormally high voltage on the kick down switch circuit, which is the signal used to command a downshift when the accelerator is pressed fully. The TCM expects a specific voltage range on this circuit and flags the code when the signal stays above the upper threshold, indicating an open circuit, a short to power, or a faulty switch.

DTC codes / P27xx · Transmission / P278D

P278DKick Down Switch Circuit High

P278D means the transmission control module (TCM) has detected an abnormally high voltage on the kick down switch circuit, which is the signal used to command a downshift when the accelerator is pressed fully. The TCM expects a specific voltage range on this circuit and flags the code when the signal stays above the upper threshold, indicating an open circuit, a short to power, or a faulty switch.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

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