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Technical Description of OBD-II Trouble Code
The issue is with the Pressure Control Solenoid B, which is operating intermittently.
What does that mean?
This is a generic diagnostic trouble code (DTC) for transmission problems. It is commonly 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. However, the repair steps may vary depending on the specific year, make, model, and powertrain configuration.
When the P0779 OBD-II trouble code is detected, it means that the Powertrain Control Module (PCM) has identified an issue 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 are P0775, P0776, P0777, P0778, and P0779. The specific malfunction that triggers the PCM and illuminates the Check Engine Light determines the code set.
The Transmission Pressure Control Solenoids are responsible for regulating the fluid pressure for proper automatic transmission operation. The PCM receives an electronic signal based on the pressure within the solenoids. The transmission’s bands and clutches change gears by having fluid pressure in the correct place at the right time. Based on signals from devices that monitor the vehicle’s speed, the PCM controls the pressure solenoids to direct fluid at the appropriate pressure to hydraulic circuits that change the transmission gear ratio at the correct time.
The P0779 code is set when the Pressure Control Solenoid “B” operates intermittently.
Example of a transmission pressure control solenoid:
What is the severity of this DTC?
Initially, the severity of this code is moderate. However, if not addressed promptly, it can escalate to a more severe level.
What are some of the symptoms of the code?
Symptoms of a P0779 trouble code may include:
What are some of the common causes of the code?
Possible causes for this P0779 transmission code may include:
What are some P0779 troubleshooting steps?
Prior to starting the troubleshooting process, 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. Additionally, checking the vehicle records to determine the last time the filter and fluid were changed is advisable.
Fluid & Wiring Inspections
The first step is to check the fluid level and examine its condition for contamination. Before changing the fluid, it is important to verify the last time the filter and fluid were changed using the vehicle records.
Next, perform a detailed visual inspection to check the wiring for any obvious defects. Inspect 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 necessitate a digital multimeter and access to the specific technical references for the vehicle. It is crucial to obtain the specific troubleshooting guidelines for the vehicle before proceeding with the advanced steps. Voltage requirements and fluid pressure specifications may vary based on the vehicle’s specific model and transmission design.
Continuity Checks
Unless otherwise specified by the technical data, the normal readings for wiring and connections should be 0 ohms of resistance. Continuity checks should always be performed with the power removed from the circuit to avoid shorting the circuit 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 hope that the information provided in this article has been helpful in addressing the issue with your pressure control solenoid trouble code. However, please note that this article is strictly informational, and the specific technical data and service bulletins for your vehicle should always take priority.
Professional Service
While we always recommend seeking professional mechanical assistance to resolve this issue, if that is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to be addressed. If you are interested in this option, please upload your ECU file to our portal.
