Electrical problems on Triumph Spitfire 1500

I first started this posting with:
Before I go completely mad, I better consult the collective wisdom here...
But then I went back and solved the problem, purely by chance. Hurray.
As a warning and education, I'll post about the problem anyway.
I have a 1976 LHD Triumph Spitfire 1500, with the old Herald/TR6 switchgear on the steering column (pre-FH100020). It's in good nick, complete and most of the time it's in perfect working order. But while driving it today, I noticed the indicators had stopped working. On closer inspection, the stop lamps, reverse lamps, tachometer, fuel and temp indicators and heater fan switch had also stopped working.
"Ah", I thought, "that'll be a fuse, then". Sure enough, according to the electrical diagram, all of these things are fed through the same fuse, the top one in a set of three. But there was nothing wrong with the fuse.
So I got out the multimeter and started doing some measurements. There was power going to the fuse (three white wires, all live) and there was power coming from it, through four green wires. But at the other ends of all these green wires, there was no power!
Bother. :-(
I really thought I was going mad, I had already started writing to the therapeutists here, when I decided to check everything one more time. My lovely wife, whose knowledge about electrickery on a scale of 1 to 10 is about -5, was watching what I was doing. As I was applying the multimeter to the wires at the back of the fuse box, she said, while looking at the dashboard, "there's something working here... oh, it's gone out now.... no, it's working again". It was the seat belt warning light, which is also fed by this fuse.
So the problem was in the fuse box. I used some tuner spray on it and everything is working fine again. God knows for how long, though. Of course it's only now that I remember a similar problem being discussed in this very newsgroup, not so long ago: http://groups.google.com/groups?threadm=cN1du4Cfel3%2BEwq4%40bedan.demon.co.uk
Yep, fuse boxes are definitely a weak point in Triumph Spitfire electrical systems.
--
Y.

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Was this with the load switched on or not? When using a DVM, you can get an apparently normal reading on a circuit which is carrying no current as a good DVM draws effectively non. Apply the load, and 'downstream' of the faulty connection, the volts will disappear.
Short of actually burning out, the wiring itself will be ok, so you're looking at a faulty connection. I'd probe through the wire insulation with a needle on one of the wires leaving the box with the load switched on - this will prove the fusebox and connections to it. It's not unknown on old wiring for the crimped connection to the 1/4" connectors to fail. Also, on the fusebox, are the multiple 1/4" outlets from the fuse one piece or riveted? If riveted, this again can corrode.
Does your DVM have a test sounder that varies the tone according to the resistance? These can be very useful for finding high resistance connections. I've got a Maplin tester that does just this and is great for car fault finding. But it was a kit and is no longer available. ;-(
--
*Hard work pays off in the future. Laziness pays off now *

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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Dave Plowman wrote:

The riveted connections are my favourite - in particular where the clip-that-holds-the-fuse is riveted to the strip wto which the 1/4-inch blades connect. It only needs the slightest bit of dampness to get in, and you get the growth of that distinctive green corrosion. At that point, as far as I'm concerned, the fusebox is scrap: I have tried cleaning the things up and running some solder round the area, but the heat from this seemed to weaken the springiness of the fuse-holder clips themselves - I've also tried using a big hammer-and-drift to crimp the rivet a bit tighter - this improved matters for about a month.
These days, I bite the bullet and replace the fusebox!
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Crikey - I've never seen one like that.

Isn't there an identical looking fuse box that uses spade connectors?

It should only bleep when the resistance is low enough to be of some use. Perhaps 10 ohms or less.

--
*The only difference between a rut and a grave is the depth.

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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Yes - this is common with general purpose DVMs. But there are custom designed continuity checkers that have a more sensible limit.

I'd guess it's indicating a possible short rather than continuity, as it were.

Yes - you need to draw a reasonable current, and this would be difficult with a battery DVM. You could, of course, wire a resistor (say about 50 ohms 5 watt) across the meter when using the low volts range which would have a similar effect.
I've got an old Maplin kit - a discriminating continuity tester which is ideal for car - and much more. Sadly, Maplin don't make kits anymore.
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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01:37:29 +0100 and decided it was time to write:

Hundreds of thousands of Triumphs had a fuse box like that. I've never seen one with a fuse box with spade contacts.

If there were, fitting it would involve an awkward rewiring job in a very confined space. Almost as much trouble as fitting a completely new front loom to the car.
--
Y.

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You CAN get a new fuse box from Canley Classics - 21 quid if I remember correctly. Had (have) much the same prob. Mine appears to be caused by one of the terminals no longer being fixed to the plastic surround, so it doesn't grip the fuse. It currently has a small piece of hardboard between the crimped ends (inside the car) ensuring that the fuse end remains tight (just passed MOT like this!) I have bitten the bullet and bought a 16 way blade fuse box, so I can give each circuit it's own fuse - but that not a summer job! In article

--
Steve Golab Bedan Limited
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I currently experience a similar problem with my '78 Spitfire. Brake lights and internal dashboard lights are controlled through fuse number 2 in the fuse box (the Lucas type located under the bonnet). Dirty contacts make light flicker. I also experience loss of power in RPM, fuel, engine temp gauge once in a while when I use the turn signal.
Paul
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