P278C: Kick Down Switch Circuit Low
The P278C code indicates that the powertrain control module (PCM) has detected a low voltage condition in the kick down switch circuit. The kick down switch is typically located on the accelerator pedal assembly and signals the transmission to downshift when the pedal is fully depressed. A low circuit voltage suggests a short to ground, faulty switch, or wiring issue, which can prevent proper downshifting and affect vehicle performance.
01. Most Common Causes
- Faulty kick down switch
- Short to ground in the kick down switch circuit
- Damaged wiring or connector
- Corroded or loose electrical connections
- Faulty PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission fails to downshift when accelerator is fully depressed
- Reduced acceleration or sluggish performance
- Transmission stuck in a single gear (limp mode)
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P278C and check for other related codes.
Step 2: Visually inspect the kick down switch and its wiring for damage, corrosion, or loose connections.
Step 3: Test the kick down switch with a multimeter for proper resistance and continuity.
Step 4: Check for a short to ground in the circuit by measuring voltage at the switch connector.
Step 5: If wiring and switch are okay, test the PCM input/output signals to rule out a faulty PCM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause transmission shifting issues, reduced performance, and potential damage to the transmission if driven aggressively.
How much does it cost to fix?▼
The cost to fix P278C typically ranges from $50 to $150, including parts (kick down switch) and labor. Diagnostic fees may add $50-$100.