TR6 Tech Forum

You might try some contact cleaner spray on the switch, but that is the least of my concerns.

As skootch mentioned, the connections to/the harness at the pigtail of the switch wiring would be something to look at.

Either way, the headlights being supplued by that purple circuit is not right. 60/55w (4-5A)flowing through it full time when on.

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74 TR6 aka Mr. T.
Clean stock, with a few peaks and tweaks.

Tom,

You see that brown wire on your switch? See how it goes straight down? I had to order 3 or 4 switches until I got one that did that. If the wire goes straight out, it will rub on the steering shaft. Not good because brown is always hot and unfused. I happened to catch mine a year after putting in the first and had to get into the steering wheel for some reason that I can't remember.

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1972 Sapphire Blue TR6

1973 MGB Rover V8 LT 77

A picture is worth a thousand posts

Found the pic.

You don't want this.

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1972 Sapphire Blue TR6

1973 MGB Rover V8 LT 77

A picture is worth a thousand posts

Instead of throwing parts at it, why not just take it to a local mechanic and have them check the hot fuse box?

just google 7fj lucas fuse box

Tom,
I looked in my copy of the Triumph TR6 TR250 TR5 TR4 TR4A Repair Operation Manual
Publication Part No. AKM3646
copyright 1977

on page 86-46
section 86.65.17
Column Light Switch - remove and refit
paragraph 13


Connect five snap connectors as follows:
Brown/Blue switch wire to Brown/White with a small Blue indent main harness wire.
Red/Green switch wire to Red/Green main harness wire.
Blue switch wire to Blue main harness wire.
Brown switch wire to purple with a small Brown indent main harness wire.
Blue/White switch wire to Blue/White main harness wire.

Then I looked in my copy of the
Triumph TR6 Repair Operation Manual
Publication part No. AKM 3529
copyright 1975

on sheet 1
section 86.65.00
at the top of the page it shows 4 wire colors from the switch N NR UR UW
position
Headlamp NR to UW
position hed dip U to UR
Position head flash N to UW

You mentioned you tend to analyze things before deciding on what to do. I just thought you may find the information listed above helpful. There is more pinpoint accuracy to be had with more detailed voltage drop tests if you are so inclined.



Edited 1 time(s). Last edit at 2024-07-02 08:11 PM by tirebiter.

Jeff,
Thanks for taking the time to provide details from the service manuals. Much appreciated. Yes, I can probably use that info once I receive the new switch. The guy I bought my '72 from gave me a disorganized service manual, probably one of the two you referred to. I guess I need to take the time to reorganize it and put it back together. I don't think it has a table of contents or index and the sections aren't in the correct order, but I have stumbled upon some helpful information.

Tom,
Have you considered cleaning the contacts on your switch vs replacing it?

If the binding is all coming undone it might be the same manual from 1977. Pages started detaching from the binding very quickly after I bought mine brand new way back when. The pages go by section number and are all sequential. No page numbers.

I finally got around to checking out the wiring harness under the dash where the headlight switch wiring sleeve joins the harness. I think I've finally found the root of the problem and it was just as suspected by skootch, tirebiter and Ken. It was the wiring connections information provided by tirebiter (thanks a million!) that allowed me to identify the incorrectly connected wires from the headlight switch to the harness. According to those specs from the Repair Operation Manual publication AKM3646 the brown/blue wire and the brown wire from the switch are incorrectly connected to the harness wires. I've attached a couple photos. The 2nd photo shows a section of the brown wire from the switch which has apparently become so hot that its begun to melt! I was so elated to find this issue after all of my searching and head scratching, and glad that nothing caught fire.

I've ordered a new headlight switch and fuse box from Rimmer Bros. I received confirmation of the order and that it will arrive in 5-50 days. That's a nice wide window Rimmer gives themsleves but I guess it's mostly the unpredictability of international shipping.

In the meantime I'll try to disconnect the two incorrect connections from the switch, reconnect them correctly and see what happens with those !#%&* fuses that have been getting so hot.

Thanks to all of the great contributions to this thread! I really appreciate all of the information so freely shared by other enthusiasts on this forum. It's a great source of information.

Added an updated photo identifying incorrect connections from switch to harness.

The big question is ....
Do the fuses still get hot ?

Jeff - After swapping the headlight switch-to-harness wires per the details you provided I am very pleased to report that the purple circuit fuse does not get hot with parking/headlights turned on. Yahooo! But the red circuit fuse still gets hot w/lights on. And another puzzling result of swapping those two connections from the headlight switch is that the flash-to-pass function no longer works. What the heck!

I also did some testing of the red circuit by disconnecting parts of the circuit like the front park/marker lights and the rear half of the harness at the driver-side footwell kick panel, but those tests produced inconsistent results. The connectors for the front park/marker lights were reasonably clean when I disconnected them. I gave them a cleanup with a brass bristle brush and rolled-up emory paper to get inside the female connector, then put a little dielectric grease on them before reconnecting.

Andy - I also unmounted the fuse box from the fender to double check connections behind it, in particular the soundness of the rivets connected to the fuse clips. The rivets were all tight and the fuse box looks relatively new, definitely not original. I'll rethink how to go about testing the red circuit connections. I'm going to try to disconnect the rheostat for the dash lamps to take them out of the equation. Any pointers would be appreciated.

Paul K - Can you explain how I can perform resistance or Ohms testing on those components? You and others have mentioned this previously but I don't know what results I should expect and what results would indicate a problem. I have an inexpensive Autocraft digital multimeter and wondered if I need to invest in a better meter.

Heading back to the garage. Going to first check to ensure I didn't disrupt the connection for the headlight flasher cable (blue/white) to resolve flash-to-pass not working after swapping connections from the headlight switch.

Thanks!

Just a quick update for anyone who is following this saga. I go out to the garage to pick-up where I left off yesterday, first task to research why the flash-to-pass function stopped working after correcting headlight switch connections and low and behold! the flash-to-pass is working again! I guess the gremlins left after I finished yesterday. Nothing changed from my perspective since yesterday. The gremlins are winning right now.

Dielectric Grease - It is an insulator and not a conductor. Use it after you make the connection and around it, but not on the conductors themselves.

Not the problem you are seeijg, but wanted to clarify that as you move on in diagnosing and cleaning things up.

You're doing great!

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74 TR6 aka Mr. T.
Clean stock, with a few peaks and tweaks.