Cause
Faulty kick down switch
The full-throttle downshift request. On older automatics it is a physical switch under the accelerator's last centimetre of travel; on newer cars it is a firm detent at the end of the pedal sensor's range that behaves as one. Either way it corrodes, sticks and falls out of adjustment like any switch that lives on the floor of a car — and the failure only shows at full throttle, which is why it survives every normal test drive.
Check the cheap explanations first: a floor mat riding up under the pedal, a switch knocked out of adjustment by footwell work, a corroded connector. Where it is a separate part it is inexpensive; on pedal-sensor cars the repair is usually the pedal assembly.
Typically a moderate job.
Codes this can cause (5)
Codes where this is a likely explanation first, rather than merely a possible one.
- P278A Kick Down Switch Circuit Likely for this code Low
- P278B Kick Down Switch Circuit Range/Performance Likely for this code Low
- P278C Kick Down Switch Circuit Low Likely for this code Low
- P278D Kick Down Switch Circuit High Likely for this code Low
- P278E Kick Down Switch Circuit Intermittent/Erratic Likely for this code Low
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Others who found this
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about Faulty kick down switch.