855 tailgate harness and how to fix Topic is solved

[Clemens]

Dear fellow Volvo-cons!

I noticed the other day that the cargo compartment dome light in my wagon was on or off depending on the angle of which the tailgate was. A quick check revealed a few broken wires in the wiring harness that goes into the tailgate. My natural approach as an RC racer with 25 years of experience with a soldering iron would be to solder the wires and insulate them with shrinking tube. Is that a good idea? I heard people say that soldering wires in a full scale car isn't good due to vibrations.

Also, what is the best way to access the wires? I read that the wiring harness has a connector behind the d-pillar tweeter.
If I disconnec this, can I pull the harness out w/o removing the tailgate?

Thanks, Clemens

[BEJinFbk]

I haven't had to tackle this particular job,
but I have repaired a ton of jamb to door
harnesses in a wide variety of vehicles.

In my environment, the fix that you'll never
have to touch again is replacing the portion
of the harness that flexes with better wire.
Be sure to go far enough beyond the flex
point with the good wire to avoid trouble.

I usually find solid anchor points at each end
of the flex run and break out the T&B Ty-Wraps
to isolate the regular wire from movement.

And I'm right with you on soldering and shrinking.

Around here, I usually get that wire by stripping
the conductors out of SJEOOW cord. Look for the
all weather extension cord that's blue with a red
stripe. This stuff is Amazing. It still flexes nicely
at -50 and is rated for use down to -94.
Something like this:
https://www.amazon.com/US-Wire-Cable-99 ... 29&sr=8-24

You can also get a wide variety of gauges and colors
individually, but procurement can get cumbersome
for small jobs. IE: These guys have a great selection:
http://www.polarwire.com/aufb-single.html

Of course, this is all my crazy, OCD overkill,
but having inop stuff in the middle of winter
is often remarkably inconvenient...

[Cookeh]

Combine the soldering and heatshrink steps by using solder sleeves. Massively simplifies things and you'll never look back.

As for the method, I too would be interested in greater detail than most posts cover as I believe some of mine are going. Most posts just state to remove the d-pillar trim (so the top trim piece with 2x T25s by the rear light, and then the LHS D-pillar, via a T25 and lots of brittle clips), before cutting the harness sleeve open to get access to the wires.

[Clemens]

Thanks for the help. I went ahead and resoldered the wires and shrunk them. Everything works again. Even the rear wiper that I had suspected as faulty.

It is actually doable to solder the wires w/o disconnecting the d-pillar connector, but removing the d pillar trimnand freeing the wires helps alot.
Now I might as well go ahead and replace the faded tail lights and the saggy tailgate shocks.

[Clemens]

Wow, these fora are awesome. I had totally forgotten that I did that job 2 years ago

[abscate]

Wow, these fora are awesome. I had totally forgotten that I did that job 2 years ago

That’s been happening to me, too. Stop that, Matt!

[Oly850]

The tailgate wiring fix for the dome light or the wiper is extremely common. I’ve done it on early V70 hatches, 850 doors, 240 & 740 hatches too. Just a natural weak point. On wagons I remove the interior trim and get as much wire exposed as possible and splice in a longer piece so that the repaired section of the old wire is no longer at the flex joint.

[jreed]

I'm doing a similar repair now on my 855 tailgate wiring, where the large diameter yellow/red wire powering the rear defroster broke. I soldered in a splice and taped the extra wire to the bundle... will post a picture here. I've got the trim off for now and am testing to make sure it works well and is a stable repair before reinstalling the trim.

[jreed]

Here are some images of the defrost circuit wiring repair on my '97 855 GLT, showing a red wire spliced in with solder/heatshrink to repair the broken original yellow/red defrost power wire. I wrapped the splice to the original harness using "gorilla" tape (super sticky duct tape).

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The small red tie-wrap is not necessary... it's just a visible reminder for me to keep an eye on the hinge and make sure the repair is holding up.

[scot850]

Tailgate and trunk repairs are a lot of fun............!

Neil.