How to Install the Temperature Sensor on a Ford 4R100 Transmission

Park the Ford on a level, paved surface and set the parking brake. Set wheel chocks behind the rear wheels. Place the transmission in neutral. Raise the front of the Ford with a jack and support it with jack stands.

Place a drain pan under the transmission pan. Remove the drain plug with a ratchet and Allen bit. Be careful not to burn yourself with hot transmission fluid. When the fluid has drained, install the plug, and use a torque wrench and Allen bit to torque the plug to 18 foot-pounds. Wipe up any spills with shop rags.

Remove the bolts from the transmission pan with a ratchet and socket. Remove the pan. If the pan is stuck, carefully slide a flat-head screwdriver between the pan and transmission to break it loose. Remove the gasket and wipe the gasket surfaces on the transmission and pan with a shop rag. There should be no sealer on the gasket. Wipe out the pan with a shop rag.

Grab the transmission filter. Turn and pull on the filter at the same time to remove it. Make sure the filter seal comes out with the filter. Sometimes it gets stuck in the transmission. If it does, insert the filter back into the transmission. Twist the filter back and forth while pulling the filter from the transmission. As you pull the filter, apply a little pressure against one side of the seal. It may take a few tries to get the seal out. The seal is a light-colored rain that fits on the end of the filter. Look at the new filter to see what the seal looks like.

Disconnect the electrical connector from the temperature sensor. The sensor is located between the two shift solenoids on the passenger side of the transmission. Push in the tab on the sensor, turn it counterclockwise and pull it out.

Coat the O-ring on a new sensor with fresh transmission fluid. Install the sensor and turn it clockwise to lock it into place. Reconnect the electrical connector.

Push a new filter into the transmission. Place a new filter on the pan. Do not use any sealer. You can keep the gasket in position by slightly installing several of the pan bolts until they are just past the edge of the gasket. The gasket will hold the bolts in place.

Mount the pan onto the transmission and start the bolts. Install and start the rest of the pan bolts. Work your way around the pan in a crisscross pattern until the pan is in contact with the transmission. Use a torque wrench and socket to torque the bolts to 11 foot-pounds, working in a crisscross pattern.

Raise the front of the Ford, remove the jack stands and lower it to the ground. Slowly add 7 1/2 quarts of Mercon V transmission fluid to the transmission. Start the engine and move the gear selector into each gear. Allow the engine to reach normal temperature and recheck the fluid level. If more fluid is needed, add 1/2 pint at a time until the proper level is attained.