TR6 TR6 Electrical Problem

Having a spot of trouble. /ubbthreads/images/graemlins/confused.gif
The fuse fed by the white cable that protects the following circuits keeps blowing:
Stop Lamps
Reversing Lamps
Windscreen Wiper
Windscreen Washers
Temperature Indication
Fuel Indication
Heater
Turn Signals

The strange thing is it doesn't happen at any particular time, i.e. when I use the wipers or use the turn signals, etc. Sometimes it blows on turn of the ignition key, sometimes I can be driving for 1 hour or so without it blowing.
Any advice would be appreciated.

Until you can reliably recreate the problem it will be difficult to do much about it.

You can rig up a test lamp to bridge the fuse location that will at least spare you going thru a lot of fuses while you test things. I think you may be looking for a short rather than an overload inasmuch as it is not associated with turning on any particular device.

With everything off the lamp is of course off. If you fiddle with the wires and recreate the short the lamp will glow brightly -- the visual equivalent of a blown fuse.

If fiddling with the wires doesn't produce a bright light (short) then start switching on circuits with more fiddling.

An assistant to watch the bulb will be useful (the assistant should probably be familiarized with how to pull the ground cable off the battery if things get lively).

As someone once said... mechanical problems take minutes to diagnose and hours to fix, elctrical problems take hours to diagnose and minutes to fix.

Stuart,
Went through the same exact problem with a TR6 that I was considering buying. Had a mechanic wizard friend check it out as to why the darn thing kept blowing the same fuse as yours. The advice given in the above post is very sound. You have a short somewhere and just need to unplug each end-user on that circuit. The problem of it happening intermittently makes it hard. You obviously must be using that particular circuit when it blows. The culprit in this car was, of all things, the windshield wiper motor detent circuit, the one that makes the wiper blade go home when turned off. We cut that wire and it temporarily solved the problem. I didn't buy the car, by the way. Close inspection showed that it had been wrecked in years past and the frame bent.

Bill

Hello Stuart,
if you are still experiencing this problem after following the advice above, you may like to split all the circuits and add a temporary fuse to each one. If and when the problem appears you will at least know what circuit is the culprit.

good luck,

Alec /ubbthreads/images/graemlins/thirsty.gif

I had a similar problem with my GT6 once. It turned out to be a short in the harness leading to the rear of the car. Right under the driver's seat the insulation had worn off of a wire and whenever I hit a bump the circuit would short out. /ubbthreads/images/graemlins/eek.gif I'd look there first for your short too.

Thanks for the pointers.
The test lamp was an excellent idea. Bought one from Schucks for $2.49, save loads on fuses.
The end user quote got me thinking. I tested all the items on the circuit, the lamp still lit. The only constantly on items are the fuel gauge and the temperature gauge, no problem there, so what about the voltage stablizer being the problem? I've got one on order to replace so watch this space.
Thanks again.

[ QUOTE ]
...what about the voltage stablizer being the problem?

[/ QUOTE ]

You could unplug it and see if that makes a difference. Anything is possible but I wouldn't expect the temp and fuel gauge to work correctly if the stabilzer had failed.

Remember that even though things are off the wires to them may be hot when the ignition is switched on (as is the ignition circuit itself). If it is the same scheme as TR3s & 4s -- white wires, green wires and prehaps others.

Tedious, but I think you may have to undo sections of the harness one by one until you find the culprit. If you do not have a correct wiring diagram this would be a good time to get one.

Hello Stuart,
I would very much doubt that the fault is in the voltage stabiliser, that is on all the time the car is running.
I would repeat that the best way of tracing a short that you seem to have is to split up the circuits. Even if you only use one extra fuse and put half the circuits onto it, then keep halving the circuits to the fuse that blows. In my experience as an industrial electrical technician, that is the quickest route.

regards,
Alec /ubbthreads/images/graemlins/thirsty.gif

It wasn't the voltage stabilizer as piman doubted, but I did relocate the unit in the engine compartment from the rear of the speedo, what a stupid position that is!!
OK, I've fiddled, prodded, pulled, pushed and disconnected every end user, it still blew, then yesterday for no apparent reason everything was fine, and still is. Not sure what I've done but it seems to have corrected itself!!

Stuart,
There's not a chance that you are using US style fuses in your fuse box. The blow rate on these are different than UK fuses. Definately only use Lucas-style fuses and make sure the clips are clean and not tarnished. Too, I highly recommend Dan Masters' book on electricals for the TR250/TR6. The absolute bible on electrical problems as well as accurate wiring diagrams for each year. He can be reached at <danmas@aol.com>. There's nothing in it for me, he just wrote a really easy to read, detailed book.

Bill

Bill

Also, if indeed you did all that movement with your harness and this is the original harness, you surely might have a wire shorting out and it would take forever to unwrap and locate the problem. Might be easier to rewire with a new harness. Not that hard to do.

Bill