What Does P278A Mean?
The transmission control module has detected a fault in the kickdown switch circuit. This switch allows forced downshifts for passing power when the accelerator is fully depressed.
Common Causes
40%
Faulty kickdown switch at accelerator pedal assembly
30%
Wiring harness damage, broken wires, or poor connections to kickdown switch
15%
Misadjusted or improperly installed accelerator pedal/kickdown switch
10%
Corroded or contaminated switch contacts preventing proper operation
5%
Transmission Control Module internal fault or ground circuit issue
Diagnostic Steps
1
Step 1: Monitor kickdown switch status in live data while slowly depressing accelerator pedal to full throttle
2
Step 2: Inspect kickdown switch connector for corrosion, bent pins, or moisture intrusion
3
Step 3: Test switch continuity and resistance using multimeter at various pedal positions
4
Step 4: Check voltage supply and ground circuits to kickdown switch
5
Step 5: Verify proper accelerator pedal mechanical travel and switch actuation point adjustment
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
The transmission control module has detected a fault in the kickdown switch circuit. This switch allows forced downshifts for passing power when the accelerator is fully depressed.
The most common cause of P278A (Kick Down Switch Circuit) is: Faulty kickdown switch at accelerator pedal assembly
Typical repair costs for P278A range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of kickdown function reduces passing ability but does not affect normal driving. Vehicle remains safe to operate.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P278A to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission Shift Control
Difficulty
Type
Generic (SAE)
Recommended Tools
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