Help please re brake lamps.

I have a problem with my brake lamps, perhaps you can help.

1992 110 200 tdi defender.

Tail lamps work ok.

With tail lamps off the brake lamps work fine.

With tail lamps on, when the brake pedal is pressed, the nearside lamp goes off.

I have replaced the old lamp unit with a new lamp unit and bulb with no change.

Have done some testing and there is power to the black and the red wires going into the lamp but no power to the green / grey wire.

Is this likely to be a short which I need to find, or is it something more complex?

Your thoughts would be appreciated. And yes I am a novice!

Viking 210

most likely a bad earth. easy enough to check, use a spare length of wire as another earth wire. connect it anywhere on the lamp (metal) body and the chassis.

Bad earth - thanks for that will investigate first thing in the morning, due back for it's re-test at 3pm.

B*&^%y landies!

Found that there was indeed a problem with a bad earth by rigging up a link from the existing earth to a good earth - got the rear lamps / brakes working fine.

Then created a permanent attachment to the new good earth and everything fine. Went out two hours later to go for the MOT, did a final check - no brake lamps at all, no indicators (but hazards ok) and no interior light!!!

So no MOT but a bruise on the forehead - think banging and wall.

He He it's good here 'int it.

looks like you may have blown a fuse?

check the lampholders carefully, there may be a short there somewhere.

You do have to just laugh at things like this don't you?

At least it keeps me away from the crap on telly.

funny you should mention that. i havent seen any telly since last january.
about the same time as i bought the disco.

whats a telly do then?

Success at last.

Having chased shorts and blown fuses around the vehicle for two days found a short in the tow socket which seems to be the cause of the problem.

Nice shiny MOT.

Thanks for the suggestions which helped a lot.