Transmission Solenoid N91 or #4 TCC. Are you experiencing hard shifts, soft shifts, no shifts or different shifting conditions from when your transmission is cold to hot? The solenoids are prone to failures that will give you these symptoms and they are only rated for 100K miles. ***Please note that the solenoids control the valves in the valve body. If you have a bad valve new solenoids will not fix it. From my experience 99% of the time the solenoids are bad, not the valves in the valve body. Make sure you get the correct fluid to complete your project. As a professional tech I recommend replacing all of the solenoids, filter, gasket and new fluid. You can find the complete kit on our site. Do it once and be done for another 100K miles. We also offer rebuilt valve bodies with a lifetime warranty.