What it means
The kick-down switch signal jumps or drops out intermittently. 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.
At a glance
- Usually lights the check-engine light
How it works
The kick-down switch signals a request for a lower transmission gear during hard acceleration. P278E sets when the controller sees that switch signal jump, drop out, or change inconsistently instead of remaining stable in each switch state.
Common causes
Most likely first.
- Switch connector not fully seated
- Worn switch contacts
- Connector with intermittent contact under vibration
Symptoms
- Check engine or transmission warning light may be on
- Kick-down response may come and go
- Delayed or inconsistent downshift during hard acceleration
How to diagnose it
- Read freeze-frame data and monitor the kick-down switch status on a scan tool while operating the pedal through the switch point.
- Inspect the switch connector for a loose fit and check its wiring for chafing, moisture, damaged seals, or terminals that have backed out.
- Move the harness and connector gently while watching live switch status to locate a vibration-sensitive interruption.
- Check the switch contacts and connector continuity through repeated operation for dropouts, following the manufacturer's test procedure.
- If the switch and wiring remain stable, inspect the controller connector and input circuit for intermittent contact.
Common fixes
- Fully seat and secure the switch connector.
- Repair loose, corroded, or damaged connector terminals.
- Repair chafed wiring and secure the harness away from vibration or moving parts.
- Replace the kick-down switch if its contacts intermittently open.
- Repair the controller input connection if testing confirms intermittent contact there.
Can I keep driving?
If the vehicle shifts normally, limit hard acceleration and arrange a repair soon because kick-down may come and go or cause an inconsistent downshift. Avoid driving if the transmission begins shifting unpredictably.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.