Strange one this !! won't turn off if lights on ??

I would be gratefull for your thoughts electrically minded people,
Disco 300tdi, '97 manual, manual fuel pump,
vehicle starts and drives fine, no heater plug lights on dash, and turns off by key ok, until you turn on lights.
Turn lights on and it carries on running even if key removed from ignition, turn lights off and engine stops,
any ideas please.
(someone has bypassed fuel stop solenoid and also cut and rejoined all the immobiliser wires to the spider, under drivers footwell cover)

Hi, I had exactly this a couple of week ago, turned out it was the rear offside light.Some one had forced the wrong bulb in there...put the new one in and it turned off fine...check all your bulbs at the back...cheers

could be water in the light cluster or towing socket, I had the same thing years ago after a heavy rain fall, if I switched the ignition off with the lights on and my foot on the brake pedal it would keep running due to tracking through from the from the lights (unswitched live) to the brake light (switched live) thus feeeding the ignition coil (petrol). A spray of WD40 into the towing socket solved the problem.

If the fuel solenoid is out of the picture, it's a simple backfeed in your wiring.
At some point, the solenoid couldn't get powered and someone bypassed it instead of sorting it out.

Have you felt the solenoid while someone turns the key on&off? maybe the solenoid finally gave up & someone didn't want to replace it.

I'm inclined to say if it runs well, leave it alone. Who knows what else is modified.

I'd make sure everything is turned off, disconnect the battery ground @ night (in the dark) & watch for a spark when you touch the cable to the terminal on the batt.

If it arcs, you've got some load constantly, small arc = clock? thats ok.
make sure your interior lights are off too.

If you have a small or no arc, I'd leave it alone. (But I'm real lazy)

luck,greg