Any tips for installing a towing wire harness on a 95 850 wagon? Does the car come pre-wired? Or do I have to do it the hard way?

Thanks,
Andrew

 

I have a towbar on my 95 wagon, the wiring goes all the way up to the front of the car, to bypass the bulb failure relay, it doesnt look factory, but if it is it would be on the same side as the rear washer tubing (right hand side on my car)

 

Just spoke with a trailer hitch guy who sells a hardware kit to DIY or does an install for $30 more. He told me there was no prewired aftermarket set up that he knew of. You had to cut into the wires at the rear and then also run a fused wire up to the battery.
Talked to a Local Volvo dealer too and the standard old way to splice in will give you a constant bulb failure warning light. They had a kit, not plug n play but hard wired and it is set up not to give this warning. It has some sort of module that keeps things normal.
Probably much the same as the first guy I talked to just way more money.
Anyone done this?
As you can see some joker already put one in on my car and then took it out again! At least I don't have to buy the hitch.

Are the wires correct? Yellow with a silverish stripe, Red with white and green.

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I have done it. Not terribly difficult if you know how to use a circuit tester. Mine took about 3 hours, because I am super **** about running wiring, and the wire I ran to +12v power was tucked into the factory wire harness retainer that runs up the drivers side door sills. Oh, and I solder and shrink wrap everything too. Everything on my install is completely hidden - no dangling wires, etc. All in harnesses. If you're going to do it, do it right the first time.

 

In most cases you also need a converter ($30-40?) to combine the turn signal and the stop light.
Most trailers use one bulb for brake and turn signal behind a single red lens. You 850 uses a separate brake light bulb behind a red lens and a turn signal bulb behind a yellow lens. You need to take 5 wires and convert them to 4.

And you would need the converter if you're going with a flat 4 wire or the better choice the round 7-way vehicle connector. The 7-way is a more common connector for the newer stuff so if you're planning for the future it's the way to go and just pick up an adapter to the 4 flat. It's like having a half dozen hitch ***** and you still seem to be missing the one you need

Unless your trailer has separate turn signal and brake light bulbs.

 

I did it but it didn't work properly when I hooked it up to a trailer. I have to test it on another trailer to see if it works on another one.

 

Were you using a converter in your setup


A handy devise if you go with the 7-way hook up is this plug that not only converts your 7-way to a 4 but also has a row of red LEDs that light up in response to each of the circuits being energized. Let's you know if the wiring to that point is good and if your problem is the vehicle or the trailer !!



They also make them with a power port and blue LEDs.

 

I finished my install today. I needed to do it in a hurry because my Girl friend wants to use it next weekend for a camping trip. ( I sure hope the fuel pump shows up this week.)
Anyhow regardless of how you make the connections, soldered is best but the others work too, they are the same connections. I visited a local, very reputable hitch company, and bought a wire harness set up for the 850. Basically it is an electronic box that gets it's signals (for tail, brake and turn lights) from the car but does not set off the bulb warning lights. It only uses a slight amount of current draw and electronically powers the trailer lights with a direct power line from the battery.
That power wire was the most work that I had to do. I started in the trunk and worked my way forward attaching it to the Main wiring harness with tape. Under the rear seat was the hardest part and I used some wire loom. From there forward I used both the runner for the cars harness and more loom. I took the plastic door sills off and ran the wire in the gap there.
Volvo, for this car at least (93 850), is a joy to work on. Simple easy and made by a company that liked the mechanics they expected to repair them. I wish I had known this years ago.
I used a fish wire to get the wire up into the fuse box(Looking down into the fuse box with the cover removedI could see a light I had set up and poked my fish wire down toward it.) and from there drilled a wire size hole (I have 12 inch long drills but it cold be done in other ways.) to get it out to the battery. I put in a fuse link and used more loom.
The one problem I have not solved is the exit point from the trunk of the trailer lead wire ( the one you plug into the trailer.). Right now I will just hang it out and close the trunk lid. Not perfect but I do not want to run it up over the exhaust because that is the side that would work with the length of wire I have. I would love to run it over to the other side and then out the bottom of the trunk through the rubber plug that is there. I could always extend the wire.

 

Keep the wiring inside the car - just tuck it into the spare tire well, and pull it out of the trunk when you use it. From a longevity standpoint, that's the way to go. If you route it so that it's outside all the time, it will get corroded on the inside no matter what you do to it. it wont hurt a thing to pull it through the trunk when you want to use it - the rubber weather seal is more than big enough to accommodate the wire.