Thanks kindly, However I already have ALL the relevant manuals, qualifications and experience with automotive electronics, and do all my own work

That is one reason I am so annoyed. Whoever did this, for some reason, the work is half good, but half crazy, and its making it very hard to diagnose the true nature of the problem, leading me to start from scratch. I have been putting it off I admit, but it did all work, so I let it be

 

Looks like I am on the home straight.

My lighting system had the following issues

* various & worsening dropouts, with no taillights knocking me off the road (instant cop pull), probably caused by failing headlight switch (swapped in the one from my spare XJ, another on the way from Rock Auto)

* 2 x blown fuses (fuse locations and wire colors dont match up real easy to FSM )

* A dead short somewhere

*Really weird and incomprehensible wiring & relay setup.

I wasted some time trying to diagnose the issue, even knowing I would have to rip out that **** and install all new. I cannot figure out how come whoever did this used high quality connector's, all properly crimped, harnesses sheathed etc, but did numerous bizarre things, like cut the old harness, tape up the correct wire, run, new individual wires, mainly black or red, sometimes connected together, or swapped polarity

Like someone had auto electrical experience but had almost lost their mind with dementia

Anyway, it all works now, but the switch is hanging out, and the headlights and harness sitting in the engine bay, tomorrow's job

The FSM describes how to pull the HD switch, but says you need to pull the bezel (you dont), and omits to mention you MUST drop the support crossbar from dash to sidewall

Dont press too hard to undo the HD screw that fastens to the bezel, or it will push right through the brittle plastic (happened taking out spare switch)..some one else had this happen recently, I will fix with fiberglass

 

Hopefully my headlight nightmare is now over.

The night I took it out, halfway, it blew the 15A that controls, tailights, parking lights, instrument lights

Luckily, my first guess turned out to be correct, dodgy wiring in the front parking light, looks OEM, but who knows

I took my angle grinder and cut a small slot in the bowl and ran longer, thinner wires back to the original harness, so the wiring isn't crammed in there needlessly tight behind the headlight glass

My headlights are noticeably brighter, which is a relief

The new switch from Rock Auto is here already. 3 days from USA to Oz. I will probably now install it back in my spare XJ