What Does P2777 Mean?
The transmission control module has detected an abnormally high voltage signal from the upshift switch circuit. This indicates the switch or circuit is stuck in a high voltage state, preventing proper manual upshift control.
Common Causes
35%
Upshift switch internal failure causing short to voltage
30%
Wiring harness chafing or damage causing short to power
20%
Transmission control module internal fault
15%
Corroded or damaged connector pins at switch or TCM
Diagnostic Steps
1
Step 1: Use multimeter to measure voltage at upshift switch connector with ignition on - should read battery voltage on supply wire only
2
Step 2: Disconnect upshift switch and check signal wire voltage - high voltage with switch disconnected indicates wiring short to power
3
Step 3: Inspect wiring harness from switch to TCM for damage, chafing, or contact with hot components
4
Step 4: Test upshift switch operation with ohmmeter - should show open circuit when not pressed, closed when pressed
5
Step 5: If wiring and switch test good, substitute known-good TCM to verify module fault
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The transmission control module has detected an abnormally high voltage signal from the upshift switch circuit. This indicates the switch or circuit is stuck in a high voltage state, preventing proper manual upshift control.
The most common cause of P2777 (Upshift Switch Circuit High) is: Upshift switch internal failure causing short to voltage
Typical repair costs for P2777 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle remains safe to drive but manual gear selection may not function properly. Automatic shifting should continue normally.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2777 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.
