TR2/3/3A Intermitant electrical issues TR3A

[Royal_58]

I've been troubleshooting electrical issues on a 58' TR3A with Pos. ground. Trying to get the fat wires to spark, the lights to come on and turn signals to work and the horn to blow, etc., etc. The starter has always engaged and disengaged since hooking up the battery. I replaced the battery cables.

Found the wiring diagrams link posted here and I have been following the current from the battery but everytime I move a wire something else either starts or stops working. I pulled the panel out of the dash so I could get at the backside of the guages. First problem found is that the lighting switch (not OEM) seemed to not function. A bit of contact cleaner and violent actuation made the lights come on, well part of them.

Now I have headlights(don't know if high or low), LF and RF parking lamps, and license plate lamps on. Dash guages are not on or either rear tail lights. Still working on cleaning the grounds for those and haven't gotten tothe panel light switch or past that point. Now for some of the questions:

* What's the proper ground cleaning procedure?
* Should I replace the lighting switch with the "prince of darkness edition"?
* Where are the fuse sizes listed?
* Will an aftermarket point set work or do I stick with with Lucas stuff?
* Is there a simple fix for the intermitant connections or is it all in the grounding?

I'm not a spark chaser and it shows!
Duke

 

[Mickey Richaud]

Hi, Duke -

As for cleaning contacts, any abrasive will do - sandpaper, etc. Make 'em as shiny as possible, and then apply a liberal amount of dielectric grease.

Lucas stuff is really a lot better than their reputation. They do need to be kept clean and lubed, though. Most electrical problems can be attributed to poor contacts.

As for fuse sizes, a shop manual will outline them for you. Forum member Drooartz has this helpful item:

https://www.drooartz.com/index.php?page=29

 

[Geo Hahn]

1 What's the proper ground cleaning procedure?
2 Should I replace the lighting switch with the "prince of darkness edition"?
3 Where are the fuse sizes listed?
4 Will an aftermarket point set work or do I stick with with Lucas stuff?
5 Is there a simple fix for the intermitant connections or is it all in the grounding?

I'm not a spark chaser and it shows!

1 I use a small wire brush to freshen them, as noted some dielectric grease will prevent future corrosion. This is tru for both ground and hot connections -- many of those are bullet connectors which do not thrive on neglect.

2 That headlamp switch is a 2-position switch -- pull for sidelamps and panel lights, twist and pull again for headlamps. Probably cheap enough to replace that it would be worth it to most people to have the correct switch.

3 Fuses are (I think) 50 amp for the horns and 35 amp for the other (green wire items). These are British fuses, American fuses from an auto parts store use a different system (search the archives for details) but a 20 amp American fuse would be close.

4 Can't say I've noticed or heard about any serious complaints about points available -- other than that red plastic bit may not hold up as well as the original type (brown bakelite?).

5 No simple fix here. You could likely have more than one intermittent problem which will make it difficult to isolate. You are probably about to become the 'spark chaser' as you may want to give every connection a once over.

You don't say what condition your wiring harness is in. If it has many patches, frays or dodgy bits you might think about whether it should be replaced. I chased electical gremlins for years before finally replacing mine. Much easier to maintain and essentially trouble-free.

 

[TR3driver]

* What's the proper ground cleaning procedure?

For the Lucas part, a gentle wire brushing should be all that's needed. Many of them on a TR3A were originally plated with a tin alloy to reduce corrosion, and you don't want to rub through the plating. However, more drastic measures are appropriate where the attachment is to painted metal, as you do want to remove the paint.

I'll add that Triumph (not Lucas) did not see fit to supply proper ground connections to the rear lamps, and the grounds through the mounting screws are far from secure. So IMO it's a very worthwhile modification to add a ground wire to each of the rear lamps. I made a single harness that visits each of the 5 lamps, and terminates at one of the bolts that holds the fuel tank with a ring terminal & star lock washer (for good contact with the bolt).
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]* Should I replace the lighting switch with the "prince of darkness edition"?[/QUOTE]Guess that depends on how happy you are with the current switch. The Lucas switch works OK IMO, as long as you don't apply excessive physical force or have a short in the light wiring. But it doesn't take much overload to damage the switch and there is no fuse for the headlight circuit.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]* Where are the fuse sizes listed?[/QUOTE]In the driver's handbook, which was titled "Practical Hints for the Maintenance of the Triumph T.R.3".

As Geo notes, Lucas fuses used a different rating system (then) so if you want to use American fuses, AGC 20 for the fuse block and AGC 15 for the in-line holder (if your car has it) will do. But since the Lucas fuses are also slightly different sizes, it may be preferable to buy the proper fuses from an LBC vendor.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]* Will an aftermarket point set work or do I stick with with Lucas stuff?[/QUOTE]The aftermarket ones always worked fine for me, as long as I kept the point cam lubed. The 'Lucas' brandname has been sold so many times that I certainly wouldn't put any extra faith in it.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]* Is there a simple fix for the intermitant connections or is it all in the grounding?[/QUOTE] No quick fix, but it's generally not just grounding. My suggestion would be to get a (cheap) DMM (digital multimeter) and learn the basics of how to use it. After grounds, I would say that 'fixes' by the DPO are the most common trouble spot, followed by bullet sleeves that don't make good contact and broken wires. Keep in mind that you are working on a car that is some 5 times older than it's expected service life ... the amazing part is that any of the original components still work.

HF sells cheap DMMs.
https://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899
A pack of test leads with alligator clips is a very handy tool as well.
https://www.radioshack.com/product/index.jsp?productId=2062661
I keep both in the car for "roadside tech sessions".