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Triumph TR6 - wiring harness replacement

I'm starting to pull together my list of winter project, among which I plan to replace my top dash and possibly refinish my dash. I also have lots of little electrical imperfections, so I'm also thinking the easiest fix is simply to replace my entire wiring harness while I have my dash torn down. I really don't know how many previous owners there are for this car, and some of the wiring looks like it's been changed along the way.

I suspect it's going to be an interesting job. Are there any words of wisdom before I embark on this next adventure? tks


Hey Mati,

Still haven't joined , eh? You see what happened to the LAST guy that didn't join up? Just ask John in Florida. He's 4" shorter now. <G>

MARK THE STUFF!!! Get a roll of masking tape and a pen and put tags on everything. DON'T TRUST YOUR MEMORY. Take it from one who's been there (and is SO old has failing memory)...

Rememember that the easy way to test circuits (and the SAFE WAY) is to NOT HOOK UP THE BATTERY to do your testing!

It's easy really. Get your 2/10a battery charger (Sears sells a nice one for a $35 bill I think) and hook it up to your battery cables. Do this with the alternator DISCONNECTED...

With your charger hooked to the battery cables you can test your circuits ONE AT A TIME as you go along. This does two things.

1. If you DO have a problem, the self-resetting cirucit breaker on the charger will trip. Disapply power and it will reset. MUCH safer than using the battery and cooking something.

2. It allows you to SAFELY test each and every circuit on your car.

I do hope this helps,

Jim Deatsch

Have fun replacing the top dash. Are you aware the windshield frame needs to be removed?
I presume you plan to buy a new harness. Make sure you get the one for your specific year. Even then you might find some differences. It will not come with O/D wiring if you have O/D. Obviously the harness is 2 parts...front of car and back of car joining behind the driver side left kick pannel. The back harness is much simpler and probably does not need replacement. I think it would be easier to remove the wood dash (but not the metal dash). The wiring will be much easier to get at. Also (will make life easier) remove your center plinith and for needed room the seats. My wood dash is high me looks a lot richer than Mat finish...sorry..:) Also you might find you need to remove the heater assembly as the harness crosses over the top of it ( you might be able to slip it over w/o removal. At minimum remove the black heater (air) hoses.
Mati, if you wish I will fax to you a good schematic/drawing of the dash and its wiring connections...very helpfull. (what year is your 6??). You will need to change my e-mail address to to give fax # off line.
Like Jim says MARK EVERYTHING!!!! can not be overstated!!! The drawing of the dash connections I have is numbered so I simply put the same number on the wire. It actually is not all that bad as the wiring loom is to length to the individual places with the correct connections/dash lights out of the loom to that specific location. You can not really go all that wrong. The harness gets pulled out from the inside of the car out to engine bay. Replacement is reverse. You may as well replace the rubber grommet in the bulk head as you are going to rip the old one if not already in pieces. What you pull back through the bulk head can not easily be marked as you will have difficulty getting it through the hole. Best luck will be with a short piece of masking tape numbered then applied to that wire. Compare the new harness with old. Hopefully the new wiring harness is the exact colour code as the old..I do not know if this is true or not, I used the original harness. If different make note of that change.

Remove the screws holding the wood dash to the backer metal dash. You should be able to slightly pull the wood dash out ( remove steering wheel if you wish for more room) not remove the harness up the steering column just disconnect. Be carefull not to "bend/break" one of the handles to the switches on the column! With the dash out slightly you should be able to get to the back of eash gauge/switch to remove the gauge/switch from the wood dash and identify its wire/light connection wire. As you do all this, I suggest you be looking at your new harness and even do the identification on it at the same time. When wiring loom is in the engine bay you can start to replace the front of the harness with new one as you remove the old identification needed. start at the front right corner and work back to the bulk head.

The rear harness is pretty straight forward...not much to it. This harness can easily be checked from the grey MOLEX connector at the driver side pannel back. By now everyone has seen the web page for Dan Masters wiring schematics so get yours.

To me the easiest and most inexpensive way to check a wire is through the means of continuity....meaning OHM it out. Get yourself a digital multi-meter that has "continuity beep". What I did is make myself up a very long wire with aligator clips either end. Attach one end of this wire to the location being tested the other end to one lead (does not matter which one) of the muti-meter. The OTHER lead of the muti-meter is touched to the other end of the line in test...if good you should get a beep. If no beep, clean the connections and apply DG ( dielectric grease from now on guys). You will find that 99% of no continuity will be dirty connections.

Mati, you have deffinitely pick a good winter project. You will not be doing this one overnight.
Have fun and good luck.
Rick C
Rick Crawford

Your thoughts are right about doing the wiring in conjunction with the dash top. Based on my experience from last winter's projects, I agree with Rick on pulling the heater and ducting. If you have a Bentley manual, look in the back for an illustration showing where the wires connect on the gauges, switches, etc. Once I had the new harness in place, it was pretty obvious where the wires were going....that to me was the easy part. I would suggest taking pictures of the old harness in the car before you pull it out, with all the gauges and heater assembly out of the way. For me it was harder to get the harness to lay in the correct position so everything came together right. (Sometimes I wonder if it 'came together' right at the factory!?!) Take the Bentley manual to your local print shop and have the dash diagram enlarged to 24" x 36", (or the metric equivalent!) That helped me a bunch....and good luck!

Rod Nichols

Mati, you got some good advice! Now let us know how it turns out. My 71 has some electrical issues too, but that is down on my list for right now. In addition to the advice on here, what I would add is to take lots and lots of pictures. Before the era of affordable digital cameras, I rewired some stuff in an old boat we have and made a whoops which caused some damage. Now, if I work on anything like that, I take out the digital camera and shoot about 10 times as many pictures as I think I need and look at them when I get around to finishing the work.

And listen to Jim about registering! They took my name from me and everything! I used to be JohB from SoFl and now look at me. But I'm still taller than Jim, and apparently younger, although that would make Jim really old.
JL Bryan


and what do I get?

More abuse, all the time, more abuse.

Jim (woe is me)
Jim Deatsch

I had to get into the dash this summer. It was a freaking birds nest of wires. But essentially it was easy to follow and the wiring diagram makes perfect sense. Instead of replacing the harness, I tidy the existing one up; replaced poor connections, used that split tubing to segregate the wires, dilectric grease. I also by-passed teh dimmer switch. Everything works fine now. It really wasn't such a bad job and I'm glad I did it.

Hi All
I replaced my loom last year when I converted the car to RHD, I was dreading doing it but it turned out to be quite easy, most connections were pretty obvious, the only slightly awkward ones were the ones behind the dashboard instruments but I followed the colour codes in the manual and had no great problems.
The dashboard and the heater were out when I initially run the loom I then installed them and did the connections.
By the way a new loom doesn't half improve the look of the engine compartment
All the best with your job
R. Algie

Ok Jim! ok! I've registered thank very much! Even if only to avoid the fate of poor JL Bryan it was worth it.

Thanks to everyone on this post. It sounds like it's going to be an interesting job.

Rick, about your point about the windscreen, removal I anticipated, however on the issue of refit....a club member once mentioned using some type of non-adhesive sealant to prevent rain water from seeping underneath. Has anyone used a product here or can I simply bolt it back into place?

M. Holland

There's that thick rubber gasket that does the sealing. I didn't apply any sealant and its fine. One place I did mess up slightly is that I did the windscreen before the doors were on, so I couldn't center the windscreen perfectly. Which means the left window seals extra tight, and I had to cheat the right a-post seal out a lot to prevent rain from coming in. Before you tighten the windscreen back in, close the doors and roll up the windows to check.

While you have wiring and hoses out from under the dash, there's so little left you'll find it easy to work on. I replaced the 2 little heater hoses, and I cleaned and checked out the heater box and fan motor-both cheap and fast jobs. If that 30 year old electric motor fails after you put back together, a new harness won't make any difference. Isn't it that heater fan that caused you problems in the first place, or was that someone else on the BBS?

Good luck,

Mark Hauser

Ah yes, another one joins the fold offically. Let's see, John, Mati, my comissions are piling up. <G>

Mark has it just right. The seal is the seal is the seal. Check the bottom of the windscreen frame when you have it out. They like to rust (along with the top of the cowl at that point).

As it happens, I have a rather nice windshield frame, with glass, that needs a new home. <G>

Jim (raking in the comission cash)

Jim Deatsch

I had to replace the 2 little heater hoses after the full restore....beleive me It would have been a lot easier first time around. ....good point(s) Mark. Like what has been said, forget the sealant. Hopefully no horror stories when you lift the glass frame out.

GEEESS Mati, since you are doing all this you may as well just take the tub off the frame:)
Where have all the Ricks gone on this BBS or are you guys out there lerking?
Rick Crawford

Rick Free Zone

The Ricks have departed the bus. Only those of us whose names have been changed to protect the innocent remain.
Mati, for real, let us know how it goes. I am under the general impression from these boards that you have to remove the tach and the speedo to get the dash off, but maybe you can get it out enough to work on stuff. Soon, when I feel like it, I guess, I need to replace the choke cable, but I don't think that requires a dash removal. I also need to, and not soon, work on wiring. It could be a winter project, when the temp in my garage is bearable, but winter is our best convertible season. Summer is too hot, and the garage is just a big sweat pit. Maybe I can find a nice 2 or 3 week window during the rainy season!
JL Bryan

John, John,

I tole you man, bring 'er on up. It was 35 degrees here this morning.

Jim Deatsch

This thread was discussed between 28/09/2003 and 02/10/2003

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