2500 Overdrive Wiring

[Joelo]

Hi

I've seen a 2500TC which needs the overdrive re-wiring, how much of a job is this to do?

Regards

Joe

[Glenn]

In the scheme of things this should be fairly simple.  Should be... (famous last words).

If you look back through old posts, Doig started a topic about overdrive wiring.

The pre-facelift Mk2s used an A type overdrive which needs a relay but member Richard B informed us that the later J types drew a smaller current and did not require a relay.  If your TC is on it's original 'box it will be the J type.  The plate on the overdrive will tell you.

Take a positive feed from the reverse light switch green wire on the reverse light switch on the side of the gearbox.  Make sure it's the green one not the green with faint brown stripe.   Run this feed to one side of the inhibitor switch on the top of the gearbox just in front of the gear stick (which is difficult to reach when the 'box is in the car).  Run a wire from the other side of the inhibitor switch to the O/D switch at the top of the gearstick.  Connect the other side of the gearstick switch to the overdrive solenoid (round thing at the bottom of the gearbox).  The solenoid should be earthed anyway with a short black wire with an eyelet bolted to the 'box.

Check it's working by connecting a multimeter or test bulb to the postive terminal on the overdrive solenoid.  With the ignition switched on you should get 12 and a bit volts ONLY when the gearstick is in third or forth.

[Tim Bancroft]

Very difficult to reach the wiring on a bg saloon box, it will be necessary to drop the box down using a trolley jack and supporting the heavy car on subsatntial axle stands. Then its a case of lots of light and mirrors!

[Joelo]

Thanks for the replies.  From what I can gather I can use the car without the overdrive working, but I guess its worthwhile fixing it.

Im hopefully seeing the car in the next few days which leads me to my next post...

Regards

Joe