brake light problem

This may sound a bit daft - but have you got +ve & -ve the right way round to the lights, i.e. is 12V going to the pointy bit of the bulb?

Richard

yes it is the right way round. the rear lights work fine when the head lights are switched on

Does 12V still come out of the switch when it is connected to the lights? It could be that the switch has a high contact resistance,(or somewhere else in the wiring before the switch). 12V would be there with no load, but when the lamps are connected the 12V drops away.

Regards Jeff

I don't Know yet as i am at work at the moment . I will go and check during teabreak and get back to you.

just tried connecting wire from switch to rearlights while using tester and voltage dorpped to 0.also tried putting a feed straight from battery to switch and it did the same but when i put new feed straight to brake lights they came straight on.

This might sound silly but is this 2A ex military? The military ones can have a variety of switches to cut out the lights and/or stop lights for use when driving in convoy. They then only use a small light shining on the rear diff which should be painted white. I've seen many people caught out by this including those that should knoiw better. Alan

First let me check:

You have tested the in situ switch with a bulb (not a meter, you want to check that it can carry enough current) and that works?

Then you have done the same (tested with a bulb) at the back with the wire from the brake switch?

Add another wire back to the battery for the time being to get it working then spend some time later and convert to negative earth cleaning all connections as you go.

Regards

William MacLeod

So you switch isn't allowing enough current to flow? Take the wires off the switch and short them together, if the lights come on you need a new switch and can forget messing with wires :-)

Regards

William MacLeod

If am understand correctly what you have done, I seems to point to the switch having a high resistance.

With all the wiring on place, try shorting across the contact of the switch and seeing if the lights work correctly (or join the 2 wires to the switch together)

Regards Jeff

Hi again when i shorted the two wires on either side of the switch it did light the lights. So i havejust ordered a new switch through Joe Edwards and it should be here tomorrow. Thanks for all help

It a bit late now, but if your 2A had one of the pressure switches that is built into the brake pipe junction its a much easier job to replace it with a series 3 switch (which is simply a button that the pedal hits) Replacing the 2A switch involves bleeding the brakes wheras fitting a S3 one instead doesnt (and they were cheaper when i did it)