TR2/3/3A Wiring Nightmare

[STeve 1958]

I had plenty of electrical problems including no head lights. I've fixed every problem (but one) by tightening up all the plugs under the hood.
Last issue is the wipers won't turn off.

 

[TR3driver]

Oops, replied in wrong thread. Move along, nothing to see here ...

 

[RGW]

Installing a new harness isn’t that difficult. Probably the most important thing to remember is how the harness is run. If most of your old harness is in place take pictures. Put the new harness back in the same location as the old one and connect one thing at a time. When you run into a problem just ask somebody here will be able to help.

The end result will be a working and safe electrical system. Something you’re not going to have if you try to patch up someone else’s mess.

Solid advice, and thanks for encouragement. There's a side of me that just wants to take on the challenge. And you are so right, in the end, it's a much better and safer way to go.

 

[RGW]

Well, just to present the contrary view, I've always kept the original harness, even after a meltdown and/or ill-advised modifications by the previous owner. My previous 59 TR3A suffered a meltdown around 1985, so I ran new wires (all red since that's what I had on hand and I wanted to drive the car to work the next day) to the headlights and went on. The rest of the harness was still working fine when it got wrecked in 2005 (and I still rob wires from it on occasion).

The original wires on my current 56 are faded until the original colors cannot be seen; even the places where the original woven outer jacket hasn't fallen off, it's just a uniform brown. Can't even tell if it originally had a tracer or not. The previous owner removed the control head, and lopped off the harness wires to it; so one of my first tasks was to patch in new wires (robbed from the 59 harness) for that.

Unless you modify it heavily, there is nothing "safe" about the original wiring harness or a new reproduction. There are a lot of unfused wires running around, any one of which can cause a fire if it rubs on a sharp edge or whatnot. So new or old, you have to make sure that doesn't happen.

It's also easy (I find) to add wires for whatever modifications you want to make. I've done a lot of that; at the moment I think I'm up to about 9 relays, 6 additional fuses and a couple of circuit breakers (for the headlights, arranged so one breaker can only kill one light). (Yeah, I probably went overboard on the relays, but they are cheap and easy. 3 of them let the rear corner lamps do triple-duty as tail/turn/stop lamps; while I used 4 relays to feed the headlights. None are visible to the casual observer, except the OD relay mounted in the stock location.)

As always, I appreciate your input. I like your idea of adding the protection via fuses and relays. Makes perfect sense to me. Thanks!

 

[RGW]

Well, just to present the contrary view, I've always kept the original harness, even after a meltdown and/or ill-advised modifications by the previous owner. My previous 59 TR3A suffered a meltdown around 1985, so I ran new wires (all red since that's what I had on hand and I wanted to drive the car to work the next day) to the headlights and went on. The rest of the harness was still working fine when it got wrecked in 2005 (and I still rob wires from it on occasion).

The original wires on my current 56 are faded until the original colors cannot be seen; even the places where the original woven outer jacket hasn't fallen off, it's just a uniform brown. Can't even tell if it originally had a tracer or not. The previous owner removed the control head, and lopped off the harness wires to it; so one of my first tasks was to patch in new wires (robbed from the 59 harness) for that.

Unless you modify it heavily, there is nothing "safe" about the original wiring harness or a new reproduction. There are a lot of unfused wires running around, any one of which can cause a fire if it rubs on a sharp edge or whatnot. So new or old, you have to make sure that doesn't happen.

It's also easy (I find) to add wires for whatever modifications you want to make. I've done a lot of that; at the moment I think I'm up to about 9 relays, 6 additional fuses and a couple of circuit breakers (for the headlights, arranged so one breaker can only kill one light). (Yeah, I probably went overboard on the relays, but they are cheap and easy. 3 of them let the rear corner lamps do triple-duty as tail/turn/stop lamps; while I used 4 relays to feed the headlights. None are visible to the casual observer, except the OD relay mounted in the stock location.)

Not sure my response went through, so I'll repeat it here. Sorry if I'm repeating myself for no reason. First of all, thanks, and your advice on adding relays and fuses is great. Haven't had a chance to get back to my car (work has a way of eating up time), but I'll get back to it soon. Look for an update.

 

[Sarastro]

I think I'd do one of two things: first, if your electrical system has been severely...uh...customized, it might be easiest just to rip it all out and start over, as many have suggested. However, if the harness is largely intact, and just has minor modifications, it might be easiest to disconnect everything, undo the mods, and reconnect it correctly. It would be a good idea to replace connectors if you do that.

Wires do not wear out, but insulation does. As long as the insulation is pliable, not cracking, and not damaged by overheating, you can reuse the harness. The copper tarnishes and will have to be cleaned before installing new connectors, especially if they are soldered.

I reused the existing, original harness when I restored the electrical system in my TR4A. I replaced all the spade connectors and got rid of those unreliable bullet connectors. All new connectors were soldered. My only modifications were additional, modern fusing and relays. Of course, I documented everything.

 

[bnw]

Anyone remember Peter Egan, Side Glances, prom night at U of W Madison. He and his future wife were on their way to the dance in his TR3. He honked the horn and the whole wiring harness fried. She was wearing white...