Classic Thunderbird Club International
Gil's Garage
Gil Baumgartner
CTCI Authenticity Chairman
Bench Checking an Overdrive Solenoid

The overdrive solenoid can be bench checked before installing it in the transmission overdrive assembly. If it must be removed from the transmission, first remove the two mount flange bolts, turn it 90 degrees then it can be pulled out of the overdrive unit. Plug the plunger hole to prevent loss of oil.

  1. With the solenoid on the work bench the plunger will be retracted. It will measure approximately 1" long. If the plunger is extended without a power source it is defective.
  1. Connect voltage 6 or 12 volts (depending on the application) to the blue wire. Connect a ground to the mount flange. The plunger will snap to the extended position. If it does not snap to the extended position first check the power source. If the power source is good and it still does not extend the solenoid is defective.
  1. With voltage properly applied the plunger extends to an overall length of approximately 1.5" It will be .5" longer than the retracted position.
All three shop manuals have detailed operation and trouble shoot procedures for the overdrive transmissions. All the shop manuals are available from CTCI.

Gil Baumgartner

Last modified: April 19 2010