I can confirm that the hearse had the lights fitted to the bumper at the point of conversion.

As suggested before they are for use when the tailgate is open

Ah, thank you classicswede! Useful info.

Ok then, this mornings developments. I found a ring connector, so attached that to the PCB earth, cleaned everything again for the hell of it. No change.

Installed second replacement number plate light unit, as was better condition than the original working one, cleaned it all up. Light slightly brighter, otherwise no change.

Installed new earth point for the bumper lights, just to the side and below the original, with a bolt and a couple of nuts, handily located just to the side of the fuel pump inspection plate so I could get to the other side and do it up nice and tight (pics to follow, late for leaving for work!).
BUMPER LIGHTS NOW ON ALL THE TIME?!? Also dashboard now thinks there is a bulb out somewhere, even though there isn't until you put brakes/fogs on, no change there. Boot open/closed switch now appears to do nothing.

Also noticed that the indicators cause the tail lights (not brakes lights) to dim slightly when they come on.

Would it be worth running a wire from each of the rear light clusters mounting bolts to this new earth point? If we still think it's an earth problem?

Thanks guys, i'd be lost without your help!

Bumper lights on all the time sounds more correct than switching between the two sets. Yes, i'd try running a new earth from each rear cluster to the new earth point.

The bulb failure unit is probably sensing an imbalance because of the extra bumper lights, long explanation of how it works, don't worry about it for now if the lights are actually working. Let's get the lights so they pass the MoT and then worry about the bulb failure unit after. ;) :D

Hinge Wires and Rear Clusters.

Two points are further significant together:

4. There is an issue in the feed wires for the light clusters, maybe because they're cable tied to the hinge, or further upstream where I cannot see them. I’d have to take the headlining off for this which looks like a less than easy task!
6. In the rear cluster wiring, in-between the two clusters (including the number plate lamps) wires have been joined - I didn't check these, so could a dodgy connection here cause issues?

The "feed wires" alongside the hing(es). They will be prone to failure from flexing. Ask any 240 estate owner. (On the 240 there is also weather exposure.)

The joining together of wires between clusters. That is a variation of classic 240 patch up the tailgate wiring tactics. I bet you a silver three penny piece that was [an attempt] to overcome the problem of flexed damaged or broken feed wires alongside the hinges.

Bumper Lights

I get the impression from the photographs that whoever wired the bumper lights used either a towbar wiring kit, or towbar wiring components. The cable for example looks like seven core of the usual towing electrics colours. I haven't checked the colours but they look like that. Why that perspex plate with electronics is included? Are they resistors or diodes? Dunno what they are about. If you trace the seven core back you should find the origin of that wiring.

Switch

As said before me, the switch you have found is an ordinary courtesy lights switch. Is it providing an earth connection for the bumper lights? Or what? What happens if you by-pass that switch? If you take the wire to a good earth connection?

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Diodes.

Diodes. That is interesting. Someone was attempting to control current directional flow? Or, they didn't know what the components were on the useful bit of plastic they used?



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More likely trying to fool the bulb failure unit at a guess. :thumbs_up:

Stephen, thanks for your input! I've avoided looking at the wires by the hinges in the hope that something simpler would fix it, I’m hoping a new earth from each cluster will solve things as really the whole lot wants re-wiring from a good bit or wire in the hinge area downward... A job for another day, I think, I just need it to pass the MOT!

It looks a bit tow kit-esque, or maybe even trailer kit-esque but at least the bumper lights appear to work well now, tested this evening and the inside red lights each side are extra brake lights and both work.

For the courtesy light switch, when the bumper light earth was bad I think they may have been earthing through the courtesy switch, when I removed the switch they went off, but as I said they are now unaffected by the switch and it seems to have no purpose.

The feed for the bumper lights comes from the dashboard I think, it disappears under the carpet under the passenger front seat, and I couldn't see where the wires for the courtesy switch go, they don’t follow the bumper light or fuel pump etc wiring, so must go above the windows/in the roof.

A multimeter would be useful in this situation, but I don't know anything about them! Never mind owning one.

Well you are making progress. :)

A number of 240 estates have a few additional wires run to by-pass the tailgate looms until another day. It passes the MOT. ;)

If you buy a multi meter from a helpful tool seller they will talk you through the functions. And I suspect David could talk you through every function of a multi meter. You do not need an expensive one.

A test lamp is often more useful. I think it might have been in this thread that has been mentioned before. David put a link up recently, with a picture.

Herewith a thought. You want to get the MOT done and you need it sooner rather than later? You have done great progress re the rear lights. But. Is it time to ahem, pay an auto electrician to get to the bottom of those rear light electrics and get them truly sorted? It depends on priorities, you might want to conquer this yourself. And of course for all of us it depends on money.