What Does P0777 Mean?
The TCM has detected that Pressure Control Solenoid B is stuck in the on (energized) position. This means the solenoid is continuously applying hydraulic pressure when it should be cycling on and off to modulate pressure. A stuck-on condition can cause excessively high line pressure, resulting in very harsh or slamming shifts that can damage internal transmission components.
Common Causes
35%
Pressure control solenoid B mechanically stuck in the open/on position
25%
Wiring short to power causing solenoid to remain energized
20%
Valve body bore wear allowing the solenoid plunger to stick in the applied position
12%
TCM driver circuit failure holding the solenoid circuit high
8%
Contaminated transmission fluid causing spool valve to stick
Diagnostic Steps
1
With the engine off and key on, check if PCS B is being commanded on — if not commanded but still energized, suspect a wiring short to power.
2
Disconnect the solenoid connector and measure resistance and verify the solenoid is not internally shorted.
3
With the solenoid disconnected, check the wiring harness for shorts to battery voltage that could keep the solenoid energized.
4
Inspect the valve body for wear in the PCS B bore that could cause the plunger to bind in the applied position.
5
Perform a line pressure test — excessively high pressure across all ranges confirms the stuck-on condition and its severity.
Estimated Repair Cost
$250 - $1,500
Parts + labor, varies by vehicle and location
The TCM has detected that Pressure Control Solenoid B is stuck in the on (energized) position. This means the solenoid is continuously applying hydraulic pressure when it should be cycling on and off to modulate pressure. A stuck-on condition can cause excessively high line pressure, resulting in ve...
The most common cause of P0777 (Pressure Control Solenoid B Stuck On) is: Pressure control solenoid B mechanically stuck in the open/on position
Typical repair costs for P0777 range from $250 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A stuck-on pressure control solenoid can cause very harsh, slamming shifts that may damage drivetrain components and create a jarring driving experience. While the vehicle remains drivable, the harsh engagement can be startling and potentially unsafe. Repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0777 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automatic Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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