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Error Code P0776 is defined as Pressure Control Solenoid B Performance or Stuck Off, a problem usually caused by dirty transmission fluid or faulty parts.
This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, or vehicles made since 1996 up to present. Specifications on the definition, troubleshooting, and repairs of course, vary from one make and/or model to another.
The PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) controls the automatic transmission through varying degrees of hydraulic pressure, supplying the converter and shift control solenoid. This pressure is controlled through at least one electronic pressure solenoid, which is overseen and controlled by the PCM.
Basically, the P0776 is a generic code for that means the level of fluid considered necessary does not coincide with the actual amount used.
It is important to note that in some applications, Check Engine light will not be activated until several fail cycles occur.
Symptoms of this error code vary from non-detectable issues to symptoms that disable the shifting function or even torque converter clutch’s failure to engage or disengage. Of course, it also activates the Check Engine light on the dashboard. This code can also be accompanied with a “limp mode” set by the PCM. Other symptoms include:
- Transmission slippage
- Harsh transmission
- Transmission overheating
- Increase in fuel consumption
There may also be error codes relating to torque converter clutch, shift solenoid, gear ratio, or transmission slippage problems to accompany this code.
The most common cause of this error code is faulty electronic pressure control solenoid and hydraulic blockage or leaks in the internal transmission fluid passages, not enough transmission fluid, dirty or contaminated transmission fluid, or mechanical internal transmission failures. Other possible causes include:
- Malfunctioning electronic pressure control solenoid
- Electrical problem with transmission control module
- Defective or electrical problem with the PCM (rare)
How to Check
Before technicians do any significant diagnostic work, they first check the transmission fluid’s level and quality. In many cases, the problem stems from low or dirty transmission fluid. And with that, they address the problem by refilling or replacing the fluid.
After checking the fluid, technicians proceed on using OBD-II scanner to check the trouble code in real-time and see where it was first indicated. Then they reset the code, take the vehicle for a test drive and see if the code comes back. If the code comes back during the test drive, they can confirm if the original code was not a result of an electrical short or an intermittent problem.
Then they check the circuitry and wirings around the transmission control module, as well as the PCM to look for signs of damage or disconnections. They will test the circuitry using a voltmeter tool.
How to Fix
Repairs for this error code are pretty easy and straightforward, which of course, depends from the diagnosis. Repairs include:
- Repair or replacement of damaged wirings or corroded circuitry, or various faulty electrical components
- Replacement or addition of transmission fluid
- Replacement of the clutch (if it’s damaged by low transmission fluid condition)
Many times, people unnecessarily replace parts such as electronic pressure control solenoid, high pressure pump, and wiring harness in an attempt to fix this error code. Usually however, the problem is caused by insufficient or poor transmission fluid quality. Intermittent or small issues can also appear, thus, it is always important to conduct a proper diagnosis when Error Code P0776 appears.
This code can hinder the performance of the vehicle through the transmission. If the transmission is put in “limp mode” or there are other issues within the transmission that keeps the vehicle from running properly, fuel economy will definitely suffer.