Triumph Repair: Spitfire overdrive question., overdrive switch, ohmeter

Question
HI Jim you soulnd like a spitfire expert, I have a question if you can
please help me out,  I have a 80pritire with 27,000 miles my
overdrive just stop working the car shifts fine but when I hit the
switch it dos'nt switch over anymore? could it be the switch?   
thanks!   my email adresss:   (lozdeals@yahoo.com) .  

Answer
Tom,

The overdrive actuation in the Spitfire is electrically controlled, so yes, the problem might be the electrical system.  

It's possible that the switch has failed.  You can remove the switch itself by carefully removing the switch cover on the shift lever and unscrewing the switch.  A quick check with a voltmeter (ohmeter in this case) will verify if the switch itself is ok.

If the switch tests ok then you'll have to get access to the solenoid on the side of the transmission.  It's much easier to check things from inside the car, but you'll need to pull the center console, carpet and transmission cover in order to get to the transmission.

Try running the car on a deserted road (or large parking lot) with the trans cover off and see if the solenoid is making any noise when you move the overdrive switch.

If the solenoid isn't working start checking wiring between the switch and the solenoid.  If that all tests ok then it gets more complicated and you're really better off if you can have it looked at by a British car specialist.



Cheers,

Jim