P278E: Kick Down Switch Circuit Intermittent/Erratic
The P278E code indicates that the powertrain control module (PCM) has detected an intermittent or erratic signal from the kick down switch circuit. This switch is typically located on the accelerator pedal assembly or throttle linkage and signals the transmission to downshift for maximum acceleration when the pedal is fully depressed. An intermittent fault can cause unpredictable transmission behavior, such as delayed or harsh downshifts, or failure to downshift when needed.
1. Most Common Causes
- Faulty kick down switch
- Corroded or loose electrical connector at the switch
- Damaged wiring or short circuit in the kick down switch circuit
- Faulty PCM (rare)
2. Symptoms You Will Notice
- Transmission fails to downshift when accelerator is fully depressed
- Harsh or delayed downshifts
- Check Engine Light illuminated
- Reduced acceleration performance
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to verify the code and check for related codes.
Step 2: Visually inspect the kick down switch and its wiring for damage, corrosion, or loose connections.
Step 3: Test the switch operation with a multimeter; it should show continuity when fully depressed and open when released.
Step 4: Check for voltage and ground at the switch connector; repair any open or short circuits as needed.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause unpredictable transmission behavior, potentially leading to unsafe driving conditions or further transmission damage.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150, including parts (switch) and labor. Diagnosis may add an additional fee.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.