The output speed sensor works in conjunction with the input speed sensor to control the operation of an automatic transmission. If the sensors stop working, the transmission will have problems shifting, the cruise control will stop working, and the check engine light will come on. You'll want to take the vehicle to an auto shop to do a diagnostic test. If the code P0720 pops up on the diagnostic tool screen, you need to replace the output speed sensor on the transmission. This is a project an amateur mechanic who knows how to jack up a car and find the transmission can do by themselves in about twenty minutes. If you need to replace the output speed sensor on the transmission of a pickup truck, here is how to do it.

Set Truck on Jack Stands

If you are thin enough, you might be able to slide under the truck and replace the output sensor without having to raise the truck up. Otherwise, you should jack the truck up and put it on jack stands so you can crawl under it to reach the transmission.

Remove Sensor

The output speed sensor is located at the back end of the transmission. Crawl under the truck to the back end of the transmission and reach up over the top of it to grab the sensor. You want to remove the electrical connector going to the sensor first. Pull the tab up on the connector and remove it from the sensor.

You need to remove the screw on the back of the sensor to disconnect it from the transmission. You will need a T-30 torque bit and a ratchet to remove the screw.  If you don't have a T-30 torque bit, you can use a 10mm socket to wrap around the outer head of the screw. Remove the screw and wiggle out the sensor from the transmission. If the sensor won't wiggle out, use a flathead screwdriver to force it out of the transmission.


Make sure you get an output speed sensor specifically made for your truck. The new sensor will have an O-ring on the end that slips into the transmission. You should lubricate the O-ring with penetrating oil or with the same type of transmission fluid you use in your transmission before you insert it into the transmission. Place the sensor in the transmission and screw it in place. Reconnect the electrical connector.

Test Sensor

Take the truck out for a test drive to make sure the transmission works properly. For assistance, talk to a professional like Color Country Diesel Inc.