Side lights connected to stop lights

[morimac]

My van's front side lights come on (as well as the rear stop lights) when I brake. I just thought it was a harmless Morris idiosyncrasy but, unfortunately, the MOT tester didn't share my opinion. He reckons it's the wrong bulb in the stop lights but is a wrong connection from the brake switch not more likely? From the wiring diagram, the stop lights and the side lights should be on completely different circuits. Just wondering where I should start looking for the problem?

[bmcecosse]

It's either a faulty bulb at the rear where both filaments are touching - or a bulb holder with that defect - or just a bad earth at one of the rear units and the brake light is finding an earth path back through the other lamps. When the brake is applied - are the front lights full brightness - or a bit dim ?? First test then is to remove both rear bulbs and press the brake - do the fronts still come on?

[mike.perry]

Are the rear brake lights or tail lights or both coming on, are the brake lights coming on when you turn the side lights on?

[DAVIDMCCULLOUGH]

Is your van a 62 or 63 with combined brake light and indicator and the 8 way relay under the bonnet? If so I would suspect the relay.

[morimac]

Thanks for all the responses. The van's a 70 so probably no relay problem and I changed the bulbs to no effect. The stop lights don't come on when I switch on the side lights (but the side lights come on with the stop lights so I think it may be the bulb holder(s). I'm going to go over it properly at the weekend and hopefully get it sorted before I have to pay another £50 for another MOT test. I'll let you know how I get on...

[PSL184]

Bad earth on the brake light circuit.....

[bmcecosse]

Have you tried the test I suggested earlier with BOTH rear bulbs removed?

[morimac]

I tried both bulbs removed, then disconnected each, and then both, of the bulb holders. Still the side lights were coming on with the stop lights. I then started cutting back the interesting insulating tape/wire combo festooned under the chassis and lo! someone had made an uninsulated connection on the stop light wire, taped it side by side to a similarly uninsulated connection to the side light wire, then mummified the whole thing in electrical tape. Two insulated connectors later and we're all set for the MOT re-sit. Many thanks to all for the advice and help!

[bmcecosse]

Good grief...... well found !