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MG TD TF 1500 - wiring harness pieces

I have a short in my original wiring harness in the rear running lamp circuit. I am trying to decide if I should patch it up, or replace it.

The moss catalog says that the under dash portion is a separate piece. That seems to me to be a major piece. Where does the main harness end, at the fuse box ?

I am wondering if the main harness would take care of the parking lights and other things, and then I could leave the under dash portion, which looks time consuming for a later date. I will probably have to have a shop fix it.
Larry Ayres

The under dash portion (separate harness) is a small part of the overall wiring harness. The main harness runs through the fire wall close to the voltage regulator. It splits at this point and runs to the front of the car for the headlights, distributor, generator, etc. The other half runs down and back to the rear, picking up the brake light switch and a ground connection. The second piece of the main harness connects to the main harness at the rear of the car (right about at the frame cross piece). I would take a wild guess and check the connections between the main harness and the rear piece of the main harness (driver's side rear). There is one other branch of the main harness that splits off at just under the fire wall and goes to the right side, exiting the firewall at just below the fuel pump.
The separate piece that Moss is referring to is a minor piece compared to the main and connects the panel lights and some ground connections. All the wires leading to the dash are part of the main harness.

This probably doesn't answer your question. The rear tail lights, gas tank sensor and license plate light are a separate piece connected to the main harness at the rear as stated above.
Roy Challberg

Thanks,

So, it sounds as though I could replace the rear piece, which is in really bad shape.

I am not sure if this is as it is supposed to be, but it appears that the rear wiring harness was attached by the previous owner the rear mounting point for the suspension springs. This seems like a really bad place due to all of the flexing there. Does anyone know if this is correct, and where it should mount ?

regards,
Larry
Larry Ayres

Larry

Rear wiring is actually an easy one to replace. It only has a few wires. Tail/brakelight switch, wire to tail/brake light and license plate. Pretty much straight runs.

If your front wiring is good, you may want to check with someone like british wiring and see if they can fabricate a full rear harness. The rear does combine with the main, but it would not be hard to pull the new wiring through.

Issue you need to consider is the actual condition of the original wiring. These do get hard with age and it may be a better deal to replace the full harness.
BEC Cunha

I would second Bruce's recommendation of talking to British Wiring http://www.britishwiring.com/ to see if they will make up a rear harness that can be spliced into the main harness. The advantage to that approach is that what they make up for you wil be the proper color wires and all you will need to do is cut out the rear harness at a convinent point, solder on some bullet connectors and plug the two sections together. Cheers - Dave
David DuBois

Are you totally sure the short is actually in the rear section? If the rest of the harness is not in good shape, it may be better to replace the whole thing. Remember that very little is fused, and there are a lot of hot wires running around that the switch just completes the ground. My own, and the couple other original harnesses I have seen were total fire hazards. As the guys say above, the "dash harness" (avilable from Abingdon Spares) is just the wires between the dash light sockets to light switch, and a few other short jumper pieces. Time consuming to install, because of un- and re-soldering the light sockets. George
George Butz

This thread was discussed on 17/12/2006

MG TD TF 1500 index

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