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TR2/3/3A TR3A wiring

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NutmegCT

NutmegCT

Great Pumpkin
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When you begin caring for an older car, do you often find a lot of "creativity" in the lamp wiring?

My wiring diagram shows most of the leads on the lamps are correct (per color code), but a few inches from the lamp many of those leads are spliced to "incorrect" wiring (per

color code) which is later spliced to another "incorrect" color wire.

For instance ... the green/white from the engine bay harness (passenger side) is spliced to a separate solid green just next to the carbs, which is spliced to a solid red, which runs to the front right turn signal light. Per the chart the entire run should be green/white.

Also in the engine bay harness (passenger side) there's a pair of green/white lines terminating at the base of an empty female socket in the engine bay; there's no male line plugged in there at all. However, there are two green/white lines, also coming from the harness, with wirecaps on each. Temporarily patching either of the two loose green/white lines to the empty paired green/white connector results in the turn signal lamps going full on when the ignition is on. (So I quickly disconnected that!). Temporarily patching the two capped green/white lines together caused all four turn signals to flash whether the steering column switch is on left or right.

The left rear turn signal light is fed by a green/red wire which is patched to a green/white line in the boot harness, which is patched to a red/black line with a solid green two inch wire patched in the middle of it ... etc. etc.

So the question is:

As all the exterior lights actually do work correctly, except for the right rear turn signal (lamp tests ok but never flashes), is this "mix-match" of wiring something I should just shrug my shoulders at? Or is it something that needs total overhaul? A bit of the "patch and live with it" versus "rip it all out and start over" dilemma. I can't find a reference to wiring *colors* in the Judging Manual.

Thanks.
Tom
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]When you begin caring for an older car, do you often find a lot of "creativity" in the lamp wiring?[/QUOTE]
HOO-BOY, YES! /bcforum/images/%%GRAEMLIN_URL%%/mad.gif

Over the years, I've seen incredible ... er ... creativity in wiring on these cars. Tons of what you describe, with mixed colors ususally resulting from grabbing whatever scrap of wire was available to make a repair, all the way to entire wiring harnesses made from white household "zip" cord!

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]For instance ... the green/white from the engine bay harness (passenger side) is spliced to a separate solid green just next to the carbs, which is spliced to a solid red, which runs to the front right turn signal light. Per the chart the entire run should be green/white.[/QUOTE]Well, yes, except that green/white is only for the RH turn signal flasher filament. However, in some cases, the lamp itself might have only a green wire to connect to the green/white. But that's likely for later models with "hard-wired" lamps, unlike the L594 lamps you have on a 3A.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]The left rear turn signal light is fed by a green/red wire [/QUOTE]
OK so far....
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]which is patched to a green/white line in the boot harness, which is patched to a red/black line with a solid green two inch wire patched in the middle of it ... etc. etc.[/QUOTE]
Wow! I'd ditch THAT mess in a New York second! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]As all the exterior lights actually do work correctly, except for the right rear turn signal (lamp tests ok but never flashes), is this "mix-match" of wiring something I should just shrug my shoulders at? Or is it something that needs total overhaul? A bit of the "patch and live with it" versus "rip it all out and start over" dilemma. I can't find a reference to wiring *colors* in the Judging Manual. [/QUOTE]The Judging Manual is not in question here. Easy troubleshooting, safe wiring and your SANITY are the primary factors here. IF a given circuit works at the moment, and all wiring is reasonably safe, then I suppose you're ok at least for the short-term...although that doesn't help your RR flasher lamp.

Frankly, I'd spend the money on a proper new wiring harness. Lots of people like the Dan Masters "upgraded" harness, etc., but there's nothing wrong with an original type harness, IMO.

Unless you're all thumbs and color-blind, chances are you can replace the wiring harness yourself in a day or two of work. Just go slowly and carefully...and make sure you have a: the correct harness and b: the correct wiring diagram for your car.

At worst, though, I'd at least run a new wire (preferably at least green if you can't locate a length of green/white) from a known "correct" point (you should be able to patch in a test light to find a point where that wire functions correctly) to that RR flasher lamp, then just disconnect and ignore whatever goes to it now.
 
I'll second Andy's suggestion of a new harness. My TR3A had a maze of non-original patches including several 'wires to nowhere' -- just a wire snaking thru the loom but attached to nothing on either end!

A stock replacement harness was simple to install and, more importantly, very simple to follow during later work.

The usual harness may not include some bits such as the headlamp harness, dash lights and grounds behind the dash, those all these can either be obtained separately or fashioned yourself (using correct color & gauge of course).

Even on a correct replacement harness you will find 'extra' wires as they (like the original) are set-up to work for either left-hand or right-hand drive cars.
 
Yes, I fitted a new harness to a TR3 a few years ago and it was very easy. Just take it slow and follow the diagram. It is worth it for the peace of mind alone. You may find that this will help your ammeter problems or at least eliminate a wiring fault.
 
Aloha Tom,

I will second (or maybe third) the recommendation to replace the wiring harness. It isn't a hard job and may add to your peace of mind that the "smoke" will stay inside the wires. As Geo mentioned, a new harness maybe missing a few wires to replace everything. I harvest good wire from the old harness to finish the job. You can most often find a wire with the proper gauge and with the color code to match the application. For example a short piece of white wire to go from the coil to the distributor. I have found that British Wiring is an excellent source for LBC wiring needs. They offer cotton wrapped or vinyl harness, tools, and smaller bits like the head lamp harness and plug/ Here is a link to their site https://www.britishwiring.com/
 
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