Electrical: Tailgate Wiring Solution - Once & For All?

[TheHungriestBadger]

Very unlikely Bob, but then the whole aim of this solution is to bypass routing it through the hinges since that is what causes the flexing, and that is what causes the failure. This also means that one no longer has to remove the tailgate hinges to replace the loom, nor would one need to remove the existing loom - simply cut it with a pair of snips at each end and leave it to dissolve in the elements.

To clarify, the proposal here is to route them essentially through the inside of the car with a single loom hanging down on one side of the boot. This will involve running the right-hand side wiring loom across the top of the back of the car (past where the boot courtesy light is) and across to the left-hand side of the vehicle. I totally get this may not be to everyone's taste, and that's fine, but my aim is to make a more reliable, more serviceable alternative to the original installation, albeit at the cost of a slightly less discrete implementation.

Regarding the earth connections, I intend to just use a cheap braided earthing strap from Amazon or something (similar to the ones in the engine bay that ground onto the manifold etc.) and run this literally along the patch cable.

The patch cable (8 lengths of 20AWG), and the braided earthing strap would then be covered in black plastic conduit or large diameter heat-shrink or something, making the whole thing look a bit neater. The only possible flexing would then occur on the patch cable, which is completely unpluggable (i.e. you could make up two cables, and swap them in seconds if one needed repairing).

[Jungle_Jim]

This looks really good Badger, I will follow your progress with interest.

I approached this tailgate hinge wiring issue another way - and after 5-6 years it hasn't developed a problem so far...

At the time I bought some replacement looms from one of the regular parts outlets, and before fitting them immediately decided they weren't going to last too long: very rigid, the insulation inflexible, and the wires fairly thin gauge (plus they were not particularly thin strand so weren't likely to survive the metal fatigue).

So - I bought 10 metres of a highly flexible, multistrand, tinned copper, silicon insulated 16AWG (1.3mm2) cable and just made up the cabling on each side. (It didn't matter that it lost the colour-coding, I used coloured electrical tape to tag the cables at either end.) These wires all fitted ok though the hinges, and I made sure each wire was free to move around in the hinge and not pinched anywhere.

From memory I can't recall what the gauges of the separate wires in the original tailgate looms were, but because I was only buying one length of wire for the whole job, I used 16AWG so it was at least equal-or-greater than all the wires it was replacing, plus figured it might last a bit longer because it's thicker. With cabling the more strands there are the more flexible it is, plus I'd think the solder/tin coating on the copper probably makes it more resilient to the abrasion caused by rubbing together when the cable is flexed).

It was this wire or something very similar...
https://www.ebay.co.uk/itm/254836504...Bk9SR8y0io2_YQ

Please keep us updated with this, and upload photos if you can.

Thanks
John

[Jungle_Jim]

Another thought about this...

What about contact connectors a bit like what you get on the sliding door of vans like Transit vans? Or do other estate cars of any make have this kind of thing? It could be worth going around a breakers yard, seeing if anything would be suitable?

This way, wire fatigue would not longer be an issue.

Just going over the options for this perennial tailgate wiring problem...

[TheHungriestBadger]

Good shouts there Jim, certainly using thicker and more flexible cable, now that it's available, is a great alternative, especially for those who wish to/know exactly the way to remove the hinges and prop everything up or for those that want to keep the stock cable routing. Also, really handy to know the wire gauge you went with as well.

I'm certain you could use the 'spring' contacts you're talking about for want of a better word, although I haven't looked into these personally, and don't plan to either - others might wish to though, especially if they are common enough.

I'll definitely keep this space updated, but probably won't make much progress until April. I worked it out a couple days back that my current commitments with uni and jobs (excluding car bits and everyday things) is supposed to total some 66 hours/week, so to say I'm busy at the moment is an understatement 😂

[Jungle_Jim]

Good luck with all your commitments Badger.

Another thing with this is UV deterioration of the wire insulation where it is exposed in a small area in the hinge. I'm fairly certain this silicone-insulated wire i used is UV resistant. I'm not sure if the aftermarket looms are.

To be honest - it's amazing that they continued to build this body shell for nearly 30 years - making incremental improvements along the way - and yet the R&D Dept never came up with a lasting solution to this tailgate wiring problem!

[TheHungriestBadger]

This project hasn't been forgotten, currently about to move into my first non-student accommodation... Scary times, right?

So, I found a photo over on TurboBricks which illustrates the concept I'm aiming for pretty well (see attached). As can be seen, there is still some pretty extreme angle on the patch cable, hence my idea to make it socketed at both ends allowing the wire exposed to repeated flexing to be swapped in seconds if a second patch cable is made. I have acquired the 8-pin DIN connectors, both male and female, and have found the perfect wire to go with it (https://www.electricalcarservices.com/8-core-thinwall-cable-7-x-1mm%C2%B2-1-x-2mm%C2%B2-16.5/25a/p-168-280-4133). The wire in question should fit in the DIN connector as is, although I'd have to double check the specs... Regardless, I plan on making it fit. Grounding I still intend to achieve via a copper braid strap similar to those in the engine bay, and the whole lot stuck inside a sheath similar to that in the photo. Potentially there might be scope to run it along the insulation of the 8-core stuff, and ground it through the metal DIN connectors into the metal of the bodywork.

For mounting of the female DIN connectors against the D-pillar and tailgate, I plan to use Sugru given the complex geometries involved. From what I've gathered, it's like Playdoh/putty out the packet, but then sets into a hardened form, remaining mouldable in the meantime. It's available dirt cheap on Amazon as well.

I now have a cordless drill at my disposal so I expect this will get done once I'm settled into the new place before winter rears its ugly head once again. I just need to purchase some hole cutter bits, and then actually commit to doing it - how hard can it be?

Down the line I may actually pursue my crazy original idea of making an RF link that slots into the tailgate, I would just need to be able to monitor (and communicate) the status of the third brake light somehow. The bulb failure relay can be tricked by adding a power resistor under the dash somewhere, but still, it would be nice to know when that bulb has actually failed. The high-current +12V and ground requirements would be easy enough to meet with a single XT60 or even XT90 connector for extra overkill (60A and 90A ratings respectively) both of which are super easy to get hold of.

Link: https://drive.google.com/file/d/1Rbq...ew?usp=sharing

[Bob Meadows]

Brake light bulb indicator (3rd light)
If you want some indication that the high level brake light is working then this is a simple & cheap fix:~

Purchase one of the warning lights as pictured- remove the plastic cover and shorten into a small spigot fitting.
Remove the rear light case and drill the appropriate size hole to take the above. The new hole should be within the original reflector area.
Push the fitting home and snap the cover back on.

You now have an instant indication that the light is working each time you press the brake pedal.
Regards Bob.