Earth problem means third brake light doesn't work

The high-rise brake light on my TD5 90 doesn't work unless I wire a temporary earth (ground?) from the hinge side contact on the rear window to some other exposed metal on the truck. I've tested all black wires in the rear door, and none of them go to earth. Turns out the rear wiper doesn't work either...

I've traced the issue as far as a loom located behind the hinge side brake light which then disappears down underneath the truck and then along the rear cross member, but am struggling to see where is goes from there. Any pointers?

Or, perhaps a better question to ask is where do the earths from that loom attach to the chassis so that I can continue my investigations?

I know that I could just add a new earth to the rear door to fix the problem, but I'd rather see if I can do it "properly" first.

Cheers

I had another look and tracked it down to dirty contacts at the earthing point on the side of the transfer box. Everything is working now

I was just about to say they go to a little bolt on the driver's side of the transfer box but you've beaten me to it.

I have an additional earth point just inside the rear door on the tub to the door frame too and from the tub to the seat box and then to the bulkhead.

miktdish said:

I have an additional earth point just inside the rear door on the tub to the door frame too and from the tub to the seat box and then to the bulkhead.

Click to expand...

The thought occurred to me that a couple of extra earth points wouldn't go amiss. A job for another day...

It turns out that cleaning the earths on the transfer case did not actually fix the problem - I guess I just got lucky when I tested it.

I've spliced a new earth from the loom on the rear door to one of the hinge bolts. This has definitely done the trick, and the brake light is brighter than it's ever been.

I'm not a fan of workarounds, but life's too short!

BulletBrindle said:

The thought occurred to me that a couple of extra earth points wouldn't go amiss. A job for another day...

Click to expand...

You can never have too many earths on a Landie ...