Technical Description of OBD-II Trouble Code
The Pressure Control Solenoid B is stuck in the “On” position.
What does that mean?
This is a generic diagnostic trouble code (DTC) for transmission issues and is typically found in OBD-II vehicles with automatic transmissions.
This can apply to various vehicle brands such as Ford, Mercury, Lincoln, Jaguar, Chevrolet, Toyota, Nissan, Allison/Duramax, Dodge, Jeep, Honda, Acura, etc. The exact repair steps may vary depending on the year, make, model, and powertrain configuration.
When the P0777 OBD-II trouble code is detected, it means that the Powertrain Control Module (PCM) has identified a problem with the Transmission Pressure Control Solenoid “B”. Most automatic transmissions have three solenoids: A, B, and C. The trouble codes related to the “B” solenoid include P0775, P0776, P0777, P0778, and P0779. The specific malfunction that triggers the code determines the code set and causes the Check Engine Light to illuminate.
The Transmission Pressure Control Solenoids are responsible for regulating the fluid pressure necessary for the proper operation of an automatic transmission. The PCM receives an electronic signal based on the pressure within the solenoids. The transmission’s bands and clutches change gears by directing fluid pressure to the appropriate hydraulic circuits at the right time. The PCM controls the pressure solenoids based on signals from devices that monitor the vehicle’s speed.
The P0777 code indicates that the Pressure Control Solenoid “B” is stuck in the “On” position.
Example of a transmission pressure control solenoid:
What is the severity of this DTC?
This code typically starts as moderate in severity but can quickly escalate to a more severe level if not addressed promptly.
What are some of the symptoms of the code?
Symptoms of a P0777 trouble code may include:
What are some of the common causes of the code?
Possible causes for this P0777 transmission code may include:
What are some P0777 troubleshooting steps?
Prior to troubleshooting, it is recommended to research the Technical Service Bulletins (TSB’s) specific to the vehicle’s year, model, and transmission. This can save time by providing guidance in the right direction. It is also important to check the vehicle records to determine when the filter and fluid were last changed, if possible.
Fluid & Wiring Inspections
Begin by checking the fluid level and examining its condition for any contamination. Before changing the fluid, verify the last time the filter and fluid were changed by referring to the vehicle records.
Next, perform a detailed visual inspection of the wiring to identify any obvious defects. Check the connectors and connections for security, corrosion, and damaged pins. This includes all wiring and connectors related to the transmission pressure control solenoids, transmission pump, and PCM. Depending on the configuration, the transmission pump may be electrically or mechanically driven.
Advanced Steps
The advanced steps are highly vehicle-specific and require specialized equipment for accurate execution. These procedures involve using a digital multimeter and referencing the specific technical guidelines for the vehicle. Voltage and fluid pressure requirements may vary depending on the vehicle’s model and transmission design.
Continuity Checks
Unless specified otherwise in the technical data, the normal readings for wiring and connections should show 0 ohms of resistance. Continuity checks should always be performed with the power removed from the circuit to prevent shorting and causing further damage. Resistance or lack of continuity indicates faulty wiring that is either open or shorted and requires repair or replacement.
What are some common repairs for this code?
Possible misdiagnoses may include:
We recommend seeking professional mechanical assistance to resolve this issue. However, if that is not possible, we offer the option to permanently delete this specific DTC while keeping all other codes active. If you are interested in this option, please upload your ECU file to our portal.
