Techtip8

SAVVA Technical Tip no 8

Fuses to Refuse, or don’t believe your eyes!!
(Copied with thanks from the Jaguar magazine – written by Eric Fletcher)

Since June last year my TR8 has been plagued by a random indicator malfunction,
which is not funny – finding that you have no indicators in a left-hand drive car
in Johannesburg peak traffic. Simple to say – fit another indicator unit.
Of course this was done only to find that the one worked in the TR7 when
fitted to the TR8 refused to work. Eventually after trying 6 or 7 we found one that worked.

Come the next weekend, after 10kms no indicators. “Have you checked your fuses?”
says someone, “of course” is the answer and anyway why do all the other electric circuits work?
No one knows. A good friend arrives with a computerized multimeter and checks everything
and finds the fuses working and no problem in the circuits. “It must be a poor earth connection”
he decides. So a weekend checking earth connections (a TR8 has at least 16) no result.
Suddenly they are working again, happy three days and they are gone again.

It was then suggested that the “hazard switch” could be the culprit – this was
confirmed by Roger Williamson’s book on rebuilding TR7’s and 8’s. A new switch was
ordered from the UK together with some new indicator units. On arrival these items are
fitted and as someone has suggested that there could be oxidization of connectors, these are
sprayed with some expensive German anti-oxidant muti.

You’ve guessed it – no joy situation as before.

It’s now mid February and to say the least I am totally p…d off
(a Triumph owners euphemism for “distressed”). I now do something I should have done months
ago and contact an auto-electrician - who was a Lucas apprentice. Now here is where the
educational bit starts and is relevant to all English (and many American) cars.
First he checks the indicator unit – no problem. Then he checks each fuse while
they are still in the fuse box and got continuity so it can’t be a fuse. Or so I thought.
He then removed the fuse associated with the hazard and indicator circuit and held it up to the light.
It was one of the normal glass cylindrical types with the metal caps.

This particular fuse was a 25 amp and hence had a metal strip and not wire.
The metal strip was intact so what is he doing? He now examined not the sides
of the two metal end caps but their tops (where no contact is made in the fuse box). “ Got you,
you’re one of those horrors” he cries and proceeds to break the glass On doing so, only one end
of the metal fuse strip stays attached in it’s end cap – the other falls free. “There’s your problem,
Japanese or Chinese fuses.

During manufacture the wire or metal strip on English fuses is passed though a hole in the
end cap and soldered on the outside of the cap. On these other questionable fuses they have
liquid solder inserted into the cap and then the fuse wire is inserted, it does not pass through the cap.
This cheaper method of production can result in the fuse wire not being firmly fixed and
causing an intermittent connection.

Consequently, if your car has glass cylindrical fuses, we suggest that you
check the end caps and make sure they are of the English type of manufacture before you suffer
strange electrical problems