Reversing light

Hi all. Just joined this great community.
Have problem with reverse light constantly on even after isolating the switch. Must be a short somewhere! Saw a post on this site the other day with a fellow having the same issues which I can’t seem to find again. Was wondering if anyone has had this problem and if they found the cause. I have a 96 c130 300tdi. Over the years people have added wiring here and there and it’s a bit of a mess not to mention frustrating! Would appreciate any advice. Cheers

It'll be a short between something that's live and the wire between rev switch and rev light. See if the rev light dims as you switch tail/fog/brake/indicators, and look for others dimming as you do. Engine running btw. That should tell you which it is. The fault is most likely to be the entry to a lamp or the chassis, wherever wires are tightly bunched and going round a corner. If you've got a trailer socket have a good look in the back of that.

If you want to pin down which wire, disconnect the battery, take all the rear bulbs out and put a circuit tester on the centre contact of the rev light, and touch every power terminal of the back lights. Still going to have to look for the damaged wires in the rear loom though.

The wires/power to these rear lights comes from the front of the car, in the engine bay, beside the brake sevo and run into the chassis.
They pop out of the chassis at the back neatly wrapped and run up and into the rear tub, right at the back in the offside (UK) corner.
As they emerge they separate into the different cables for the rear lamps, heated screen, rear window windscreen wiper etc.
This is all behind a triangular cover.

This is where I suggest you start.

The wires for the nearside lamps travel back down through the tub and across the rear, popping up into another triangular cubby box on the opposite side.
You need to look in there too.

Take the covers off and send us some pictures ...

Thank you to those who responded. Have fixed the problem. Turns out wires were compromised at entry and exit of the chassis so bypassed the whole loom and re ran a 10 core length on top of the chassis. Once again appreciate the advice. Cheers defender bender 130