What Does P278D Mean?
The PCM has detected that the kickdown switch circuit voltage is above the expected threshold. This typically indicates an open circuit, short to power, or loss of ground in the switch circuit.
Common Causes
35%
Open circuit in kickdown switch wiring harness
30%
Faulty kickdown switch stuck open
20%
Disconnected or corroded connector terminals
10%
Short to battery voltage in signal wire
5%
Loss of ground circuit
Diagnostic Steps
1
Step 1: Check kickdown switch connector for proper seating and terminal condition; ensure no bent or backed-out pins
2
Step 2: Measure voltage at kickdown switch connector with key on - verify reference voltage present
3
Step 3: Test kickdown switch for proper operation and continuity using ohmmeter
4
Step 4: Check for open circuits by testing continuity from switch connector to PCM on all circuit wires
5
Step 5: Verify switch ground circuit integrity and resistance to chassis ground
Estimated Repair Cost
$75 - $380
Parts + labor, varies by vehicle and location
The PCM has detected that the kickdown switch circuit voltage is above the expected threshold. This typically indicates an open circuit, short to power, or loss of ground in the switch circuit.
The most common cause of P278D (Kick Down Switch Circuit High) is: Open circuit in kickdown switch wiring harness
Typical repair costs for P278D range from $75 to $380, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive with normal transmission operation. Only kickdown function for aggressive downshifting is affected.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P278D to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Transmission Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
