P278DKick Down Switch Circuit High
- Generic OBD-II code · Powertrain
- How the car detects it
- P278D means the kickdown switch circuit shows a voltage above its permitted maximum. No manufacturer documents P278D publicly. With the usual pull-up input this is the reading of an interrupted line: the pedal module unplugged after a repair, a broken wire at the hinge of a floor-mounted pedal, or a missing ground at the switch. A short to battery voltage produces the same picture but is rarer. For networked pedals the comparable case is a message that is missing or flagged as invalid, as Eaton describes for the kickdown signal of its Endurant HD gearbox (fault 167, 5 s). CARB requires out-of-range checks on such inputs. P278C is the low-voltage twin. Kickdown requests are lost until the circuit is restored.
- What you may notice
- No kickdown at full throttle
- Slower acceleration from speed
- Likely causes
- LikelyOpen signal or ground wire, pedal module unplugged
- PossibleWire broken by pedal movement
- RareSignal wire shorted to battery voltage
- Repair
- Easy · Often possible to do yourself.Typical cost: €30 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.