How to Test Shift Solenoidsby Dianne Hermance
Shift solenoids are responsible for shifting gears in a vehicle. Most modern vehicles that have an automatic transmission contain electrical solenoids that are activated when it is necessary to change gears. Most solenoids are located in the vehicle's transmission and are accessible by pulling the transmission pan. If your vehicle is having trouble shifting into drive or reverse or is experiencing shuddering when shifting, the solenoid may be defective. If you suspect a bad shift solenoid, it should be tested.
Raise up the vehicle with a jack and place jacks stands at all four corners to support it. Remove the bolts that are securing the transmission oil pan with a ratchet set and slide out the pan. This should reveal the solenoid that is attached to the transmission body.
Find the two plugs just above the shift solenoid. Unplug one. Switch the volt meter to ohms, which measures resistance. Set the volt meter to 200.
Grab the black wire from the volt meter and touch it to the negative battery terminal. Touch the positive end of the wire to the tab inside the plug you just unplugged. There are two tabs in each plug. The tab should register between 12 and 25. If it reads over or under this amount, the shift solenoid is bad. Plug it back in and test the other plug in the same manner.