P0966 Pressure Control Solenoid B Control Circuit Low
OBD-II Trouble Code Technical Description
Pressure Control Solenoid B Control Circuit Low
What does that mean?
This is a generic transmission diagnostic trouble code (DTC) and applies to OBD-II vehicles with an automatic transmission. That may include but is not limited to vehicles from Ford, GMC, Chevrolet, Honda, BMW, Saturn, Land Rover, Acura, Nissan, Saturn, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
In most circumstances automatic transmissions will incorporate at least three pressure control solenoids know as solenoid A, B and C. Newer transmissions tend to have more gears and more solenoids. Various trouble codes are associated to the "B" solenoid control circuit and some of the most common include P0964, P0965, P0966 and P0967. When the P0966 OBD-II trouble code is set, the Powertrain Control Module (PCM) has detected a problem with the transmission pressure control solenoid "B" control circuit. The specific code set is based on the specific malfunction that is detected by the PCM.
An automatic transmission is controlled by bands and clutches that change gears by having fluid pressure in the right place at the right time. The purpose of the transmission pressure control solenoids is to adjust the pressure of the fluid for the automatic transmission to operate properly and shift smoothly. The PCM monitors the pressure within the solenoids and directs fluid to various hydraulic circuits that change the transmission gear ratio precisely as needed.
Code P0966 is set by the PCM when it detects that the pressure control solenoid "B" control circuit is experiencing a low voltage condition and therefore is not functioning properly.
Example of transmission solenoids:
What is the severity of this DTC?
The severity of this code normally begins as moderate, but it can progress to a more severe level rapidly when not corrected in a timely manner. In circumstances that result in the transmission banging into gear permanent internal damage can be caused making the problem a severe issue.
What are some of the symptoms of the code?
Symptoms of a P0966 trouble code may include:
Increased fuel consumption Check Engine Light activated Transmission overheats Transmission slips when shifting Transmission shifts hard (banging into gear) Possibly misfire-like symptoms The transmission is put into limp mode by the PCMWhat are some of the common causes of the code?
Causes for this P0966 transmission code may include:
Defective pressure control solenoid Contaminated transmission fluid Restricted transmission filter Defective transmission pump Defective transmission valve body Blocked hydraulic passages Corroded or damaged connector Faulty or damaged wiring Faulty PCMWhat are some P0966 troubleshooting steps?
Prior to beginning the troubleshooting process for any malfunction you should research the Technical Service Bulletins (TSB's) for the specific vehicle by year, model and transmission. In some situations this can save a lot of time in the long run by pointing you in the right direction.
Fluid & Wiring Inspections
The first step is to check the fluid level and examine the condition of the fluid for contamination. Prior to changing the fluid, you should (if possible) check the vehicle records to verify the last time that the filter and fluid was changed.
A detailed visual inspection to check the condition of the wiring for obvious defects is next. Check the connectors and connections for security, corrosion and damaged pins. This should include all wiring and connectors to the transmission pressure control solenoids, the transmission pump and the PCM. Based on the specific configuration, the transmission
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