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 Post subject: Wiring gremlins
PostPosted: Sun Mar 26, 2017 3:22 pm 
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Joined: Thu Mar 17, 2016 11:35 am
Posts: 6
I'm trying to track down various electrical gremlins in my 61 TR 3. The problem that started it was a blown fuse, the one that protects the indicators, fuel gauge etc. In tying to trace the problem I removed both front indicator/park light assemblies including their wiring harnesses. Connections were a mess, with bare wire ends just resting in the receptors which should have a bullet plug. It's a wonder it worked at all. I fitted new (non original) bullet plugs and re-installed the lights. This resulted in a dead short and some burnt insulation behind the instrument panel cluster. I replaced the burnt wire and removed the front indicator lights again and just let them hang loose from the grille. Tested the indicators, worked fine but as soon as I turned on the park lights another dead short- ammeter pegged at 30 amps discharge. Quickly disconnected the battery with no harm done. Tried again with the same result so that's when I removed the the two front indicator light with their wiring harness.
Tested the lights again and after a few minutes same fuse blew. No short but I don't want to drive it like this.
Maybe someone has some suggestions but if not I have two specific questions;

First- my indicator/park lights each have 3 wires coming off them, one of which doesn't connect to anything. The new wiring harness picture from the TR register spare parts list has 3 wires but the wiring diagram shows only two wires coming from this assembly.
Second the Standard Triumph manual lists this fuse as 35 amps, the Haynes manual and Moss say 25. Is that just modern caution?

Thanks in advance
Peter


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 Post subject: Re: Wiring gremlins
PostPosted: Mon Mar 27, 2017 8:59 am 
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Joined: Thu Dec 19, 2013 3:40 pm
Posts: 88
The joys of original 57 year old wiring. I have not done much on the original wiring but one area I would check is the loom the travels down the center of the steering column. It caries the indicator and horn wiring and has a habit of rubbing through where it exits the column at the steering box.


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 Post subject: Re: Wiring gremlins
PostPosted: Mon Mar 27, 2017 9:05 am 
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Joined: Thu Mar 17, 2016 11:35 am
Posts: 6
Many thanks Aladdin but that has been removed and moved to switches on the dash. One thing to rule out, at least!


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 Post subject: Re: Wiring gremlins
PostPosted: Mon Mar 27, 2017 9:41 am 
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Joined: Thu Dec 19, 2013 12:18 am
Posts: 217
Fuses ex factory were 50A and 35A so suggest starting with correct fuses.

Wiring to the small lights at the front should be a red feed to each side for parkers. RH Indicator feed was green with white stripe LH indicator feed was green with red stripe. Small lights were earthed through the body, so they need to be tested in situ for the circuit to work properly. If black, unconnected 3rd wire to parkers could be a back up earth designed to improve the Prince of Darkness factor.

Task is to find where the red is shorting out. First check all connectors where everything joins up near the horns. That's a typical trouble spot. The RH & LH red parker wires just came straight from the light switch and didn't go through the fuse box at all, so something else is going on to blow the 35 amp fuse. Try disconnecting RH red parker then LH red to determine which side is giving trouble.

Try turning on the parkers with the globes out and use a multimeter on the connector to test the voltage.


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 Post subject: Re: Wiring gremlins
PostPosted: Tue Mar 28, 2017 10:35 am 
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Joined: Thu Mar 17, 2016 11:35 am
Posts: 6
Many thanks Viv for your information and erudition. I have checked as much of the wiring as I can see with no obvious faults. Both side lights/indicators are out of the car and it still blows the fuse after a minute or so. The short is what really scares me so I'm reluctantly taking it to an auto- electrician, on a trailer!

On a similar note do you (or any other member) know if installing a new wiring harness is within the scope of non- professionals? Has any one done it?
Peter


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 Post subject: Re: Wiring gremlins
PostPosted: Tue Mar 28, 2017 11:26 am 
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Joined: Mon Jan 06, 2014 10:25 am
Posts: 79
Hi Peter,
I've just done that.
To make it even harder for me I got an uprated harness that included lots of relays and extra fuses etc. When it arrived with wires going in all directions it was quite intimidating and suddenly I had to work out how a relay worked as well as finding places to put all these extra bits. Anyway to great satisfaction it's now completed and everything turns on and off as it is meant to do. And yes I'd never done anything like that before. You just need to approach it logically and work out what the wiring diagrams mean.
Cheers
Jim


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 Post subject: Re: Wiring gremlins
PostPosted: Tue Mar 28, 2017 1:09 pm 
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Joined: Fri Dec 20, 2013 10:19 am
Posts: 95
I have rewired several old cars. They are usually well tagged and coloured because the makers realise that old car people like to do it themselves. Sometimes the lengths are not quite right but usually they allow a little more. From memory the TR was also fitted with wiring for LHD because the market is world wide so you lay it out on the floor and you will see how it falls. You have to take it carefully. Best if you connect sections and see if it works rather than do the whole lot in one go. If you have the old harness in place it is best to remove it leaving a few inches of the old wiring connected at the various attachment points with the coloured wire and then label it. Sometimes the wiring does not have the connectors attached so if you leave the old connection in place it makes for a simple join. My disaster was having a short that burnt out a wire in a bundle. You can't replace that so I had to run an extra wire outside which didn't please. Hope this helps. Terry.


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 Post subject: Re: Wiring gremlins
PostPosted: Tue Mar 28, 2017 1:56 pm 
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Joined: Thu Dec 19, 2013 12:18 am
Posts: 217
Fitting a loom is fairly straight forward if not rushed. Carefully study the wiring diagram beforehand. What I found worked well was to hook up one circuit at a time. Power up each circuit such as headlights (through the dipswitch) and verify all good before starting the next circuit.

Make sure all the little bits and pieces in the control head are OK. No broken return springs etc. Not fun to having to instal it a second time.

Beware the horn circuit as it's constantly powered up. They sound when earthed via the horn button. With wiring in the steering column stator tube, the connectors have to be staggered and all wires taped up into one. Attaching a pull-through to the wires helps when feeding them down the tube.

Keep a list of each complete and tested circuit. At the end, cross reference with the wiring diagram to prove up everything in.

PS. with short circuits I've found them in the Control head, Control Box, Generator, Overdrive loom/relay, loom along the driver's floor to the rear lights, connections beside the horns, under the dash - more so if a heater fitted. Simple old school wiring though, so auto elec should find the short fairly quickly.


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 Post subject: Re: Wiring gremlins
PostPosted: Tue Apr 04, 2017 12:28 pm 
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Joined: Thu Oct 22, 2015 5:20 pm
Posts: 11
Location: Armidale NSW
A method used in the trade is to connect a light bulb say about 21watt in place of the blown fuse. Then try connecting each circuit connection while watching the bulb. If the bulb glows bright you've found the fault, if its dim its normal. I've found many short circuits are often in those light fittings where the spring earths out the wire.
All the best with it!


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