P278C
Kick Down Switch Circuit Low
Voltage on the kick-down switch line is below the expected window. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: easy
Common causes
Ordered by how often each turns out to be the cause.
- Switch wire shorted to groundCommon
- Switch stuck closedPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Kickdown Switch
- Wiring Harness
P278C is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.