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TR6 Overdrive Wiring

Gerry M

I have a 74 TR6 that a previous owner installed an A type OD. The A type OD uses a relay. There is no OD relay in my car and although the existing OD wiring works it is not wired the same as the A type OD wiring diagram shows. Rather than rewire (the existing wiring works) I am looking at just incorporating a relay into the existing wiring. I have attached a drawing of what I believe to be the correct wiring for both A and J type overdrives as well as a drawing of my existing wiring. It looks like the previous owner wired my A type overdrive the same as you would a J type. My question is how do I install a relay into my existing wiring? I think this is the same as asking how would I install a relay into a J type overdrive.

. OD Wiring Diagram1-1.jpg


Great Pumpkin - R.I.P
I guess the important question is, why do you want to add a relay? If you just want to reduce the load on the operating switch, that should be possible. But you can't reduce the load on the isolator switch unless you get down there and rewire it.
Gerry M

Gerry M

I'm wanting to add a relay because the A type OD (which I have) originally used a relay and my understanding is that the reason for that is the A type solenoid draws much more power that the J type and therefore needs a relay.

Marvin Gruber

Country flag
Ran a TR3 without relay for years with no problem and it had a generator. A type wiring is correct, no problem to put relay in as shown.

Gerry M

Gerry M

If I put a relay in as shown I will have to completely rewire my existing wiring. I'm hoping to connect it into my existing wiring setup somehow. Any advice on how best to do that. A diagram would be helpful. Thanks.
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