850 Power seat wiring - "2" questions.

[dstthomas]

I own a 1994 855/SW (850 Turbo Wagon). 152K miles.
I am fitting a Recaro seat to it. (Orthoped 2005 vintage) The original Volvo seat is very tired, and I have a variety of physical problems from a severe accident this past January.
The Recaro seat has simple wiring - apparently relatively light gauge 2-wire hookup supplying power to the switch panel.
This model seat has heated surfaces, simple fans, lumbar pneumatics, and power seat back raise/lower.
It fits into manual sliders.

Since it has heated surfaces, I am wanting to supply switched power to it. I was hoping to find at least 20A protected power.
I have been scouring this forum for other posts and I haven't found anything definitive - but I've come close.
The Volvo chassis power harness going into Control Unit "Connector A" has four wires.
The larger gauge pair is the Black and Green/Red. The black is ground, and the Red/Green is unswitched power.
The other, lesser gauge wires are Brown/Orange and what I believe to be Yellow/Violet (Which I'm guessing others have described as Yellow/Brown).
When I combine the black wire with Yellow/Violet, I do get switched 12V power.

Compared to the 25A Red/Green wire, the Yellow/Violet wire is relatively light gauge wire. I was reasoning this was not going to be great choice for heated seats. But (just looking at the diameter of the insulator) it is not an unreasonable match for the wiring in the seat. I realize that that is not a definitive assessment, but it is what I have to go on. I am studying the MEMORY SEATS CIRCUIT wiring diagram and it shows the yellow/violet is 15A connected to fuse #33. This seems a bit light to me, but I have found no way to determine what the Recaro's power requirements are.

My first question:
Can anyone suggest a better choice of higher-amperage switched current to supply to this seat that I can bring in relatively easily? I see the unused harness point under the passenger's seat. It has a "heavy-gauge" Black and green/brown wire pairing, as well as a VERY light gauge black/grey wire. I could not get power to this wire set, either switched or unswitched.
I tried putting fuses into unused/undocumented fuse holders 4, 18, and 36 and never got power there...

My second (group of) questions:
There is another connector coming out of the Volvo harness which plugs into the Volvo seat, and while I just don't know, I have been assuming that this has something to do with either determining if someone is sitting in the seat, or if the seatbelt is connected.
When I had the seat out mostly out to measure for the bracket, I don't recall noting any wiring going to the female seat belt anchor.
I've been using this car with this connection broken and i see no affect on its behavior in any way.
What is this connector for?
Can I just ignore it when I install the Recaro?
I'm pretty ignorant about this and do not want to compromise any safety features, such as air bag deployment. It seems as though this sort of connection/system became more sophisticated in later models, but does not appear to do much in my car.

I'm happy to clarify and post pictures if requested.

Thanks for your help,
Dave St.Thomas
Boulder, CO

[Ozark Lee]

Dave,


Did your old seats have the heated option - the heated seat switches on the center console? If so everything you need is there.

We have the factory service manual that has very good schematics on the site (at least we did, we cut over to a new server today).

Try this link and then look for system wiring diagrams.pdf

https://www.matthewsvolvosite.com/downlo ... vo_850.zip

...Lee

[dstthomas]

Thanks, Lee

No my buggie did not have the heated seats option, nor the heated mirrors option (which I would much rather have!).

Your post is very, very helpful.
Going through the diagrams for the heated seats, I see that the green/brown wire under the passenger seat is intended for the heated seat.
Likewise, the second "mystery" connector for the driver seat has a yellow/red, a black and the same super light gauge black/gray wire. So this former mystery connector that I had been assuming had something to so with seat belts is for heat to the driver seat. I have no idea what it is actually plugging into in the drivers, seat, though - that mystery remains.
I am taking a wild guess that the black/gray wire is for illumination - The 1995 diagram shows a pink wire - maybe the color was changed? I just don't see the super light-gauge black/gray wire mentioned. Maybe the heat wiring is present in the seat just waiting for some customer to buy a very expensive switch? The corresponding harness on the passenger seat plugs into a dummy connector.

For grins I tried to get power to the yellow/red wire, to no avail. Therefore your caveat that if I have the switch on the console, I'm in business?

FWIW, There is a discrepancy in the doc. Regarding the PDF "fuses and circuit breakers", It states (1993-95) that Fuse 18 is 25A to heated seats.
This is unused for my 1994 car, which did not surprise me. However the doc states fuse 26 is not used for my year and is used for 1996 for heated front seats and power mirrors. I have a 25A fuse in slot 26 and it is documented as being for heated front seats and power mirrors on the fuse box cover.
Adding a fuse to unused slot 18 changed nothing.

If I understand what "hot in run" means, (power supplied when the engine is running, but not in the accessory position) then...
Poring over the diagram for the heated seats, it looks like there would be a switched (hot in run) blue/yellow wire going from 25A fuse 26 to the seat heat switches. That would give me power to my beloved YEL/RED wire and I would be so very happy.

So, Lee, many thanks to you, my question now is, if I rip into the center console, is magic waiting for me under there somewhere in the form of a BLU/YEL wire aching to be connected to a YEL/RED wire? Or, is this wiring missing because the switches are not present?

It certainly appears that the the BLU/YEL wire will be available at the power mirror switches, so it is definitely running into the console.

I found a post on removing a console from (I think) an S70 suggesting it was about as simple as removing 2 screws from the storage bin - wiggle it off from the back noting how it mates into the front, and unplug the harness. I'll take a look to see if this is the same on my trusty 855.

If it were still daylight, I'd be out there now...

Many thanks for your help so far!

Dave

[dstthomas]

Thanks!
I went into the console and joined the BLU/YEL and the YEL/RED wires at the harness point to where the switch for the driver seat heat would be and I have the 25A power for my seat that I was looking for.
I couldn't be happier.
Dave