Crazy S3 Electrics

[PeterC]

Help and advice needed please. Having minor problem with electrics on car. Recently noticed (dark nights) that when I press the brake pedal, the side lights and dash lights come on?

Everything else seems to be OK.

Unlikely to be water related problem as car is only used on dry days and garaged.

Thoughts - the only commom denominator would seem to be the earthing to the chassis located behind the n/s rear wheel. But I have thoroughly cleaned this connection and problem persists.

[LeeBee]

First thing I would check would be the rear light clusters (AKA Ford Disco lights!), give them a good clean and if possible put some contact grease on the terminals.

Cheers

LeeBee

[johno]

I would further check all the earths for the electrics and then track the wiring diagram to see where these two circuits meet.

The only similar problem I have had like this is that when going to Rockingham this year for the BSB round I was following my father who after a while pulled over and asked why I kept flashing him ? It turned out that every time I hit the brake pedal it was causing the headlights to come on. What seemed to be causing it was the position of the switch for the lights. Once I switched them on and then back off and it stopped it from then on.

I must say that I have just replaced the light stalk as the internals finally gave up coming back from France, and these symptoms may be an indicator of future problems - just guessing here.

Cheers

Mark

[Greenv8s]

quote:
First thing I would check would be the rear light clusters (AKA Ford Disco lights!), give them a good clean and if possible put some contact grease on the terminals.

Cheers

LeeBee

Yes those lights used on the back are asking for trouble. Also, if you have problems with the front lights, check the connectors from the main loom to the front lights, they are interior grade connectors exposed to muck off the wheels (nice one TVR!) and mine have been no end of trouble despite being cleaned, wrapped in plastic and bundled up out of the way as far as possible. The connection for the alarm is similar by the way! As well as the mundane lop-sided lights I had more interested symptoms sometimes like the driving lamps coming on with dipped lights despite being switched off, I could switch between dazzling people with the high beem or dazzling them with the driving lights. Some sort of back feed to the relays I guess. (Hopefully the recently fitted hermetically sealed connectors will finally see an end to this problem.)

Cheers,
Peter Humphries (and a green V8S)

[PeterC]

Thanks for all the info. It will be Sunday before I can try any of the ideas.

When checking all earthing points, how many are there and where are they?

[Greenv8s]

quote:
Thanks for all the info. It will be Sunday before I can try any of the ideas.

When checking all earthing points, how many are there and where are they?

Goodness only knows, but the ones I've noticed are:

battery main earth behind the rear offside wheel (expect there's a similar one at the engine),

ballast resistors (for injectors) behind the front offside wheel,

interior loom earthed behind the front nearside wheel.

On mine the alarm is earthed on the steering column mounting bracket, but I guess this is the sort of thing that will vary from car to car. After all it *is* a TVR.

Cheers,
Peter Humphries (and a green V8S)

[PeterC]

Thanks to everyone that replied, but I think I've found the problem

The stop/tail light bulb in the o/s rear light was faulty and both filaments were illuminating when I tested the bulb by connection a 12v test battery to either contact + earth.

I changed the bulb and the problem has disappeared (for good I hope).