Voltage polarity for S70 sun visor with Homelink

[SlowLane]

While at the junkyard t'other weekend I obtained a pair of not-floppy sun visors from an S70 to replace the quite-floppy ones in my 850. As a bonus, the driver's visor has an embedded Homelink module.

Volvo considerately added 2-pin connectors for the sun visors with the S & V remodelling, which makes replacement much cleaner, so I also clipped and brought home the mating car-side connectors from the donor.

Now a conundrum: the wires attached to both the 850 and S70 visors are black (negative on my car) and red/black (positive). The mating car-side connectors from the donor car have a red wire and a black wire, which one would normally associate with positive for the red and negative for the black.

BUT, the red wire in the car-side connector mates with the black wire in the visor-side connector, and vice versa, making me wonder if Volvo had screwed up somehow in designing the Homelink visor and fixed it in the connectors. I checked a couple of S/V70s at the wreckers this last weekend and they were all the same: red car-side wire to black visor wire and black car-side wire to red/black visor wire. I tried to determine if one of the two car-side wires had a path to ground, but could not read continuity from either one to ground. The wreckers don't permit you to bring in a battery to hook up to their derelicts (good thing, too), so I couldn't measure the voltages directly.

Polarity doesn't matter to the vanity lights, obviously, but it probably does matter to the Homelink module, and I'd rather not just guess. Anyone out there encountered this before?

[RickHaleParker]

Go back to the junkyard with an Ohm meter. Connect one lead to a chassis ground. With the other lead probe the wires. You will get continuity between the chassis ground and the ground wire. After that positive can be determined by process of elimination.

While your are in the junkyard, be sure to observe the position of the pins and wire colors in relation to the plastic connector.

Do the same with the 850.

[SlowLane]

Go back to the junkyard with an Ohm meter. Connect one lead to a chassis ground. With the other lead probe the wires. You will get continuity between the chassis ground and the ground wire. After that positive can be determined by process of elimination.

I did exactly that, as I mentioned in my original post.

I tried to determine if one of the two car-side wires had a path to ground, but could not read continuity from either one to ground.

Neither of the connector terminals showed continuity to ground, but perhaps I didn't choose a good ground. I thought that the bare-metal center console frame bolted solidly to the car body would serve well enough. Silly me.

While your are in the junkyard, be sure to observe the position of the pins and wire colors in relation to the plastic connector.

And again, I thought I made it pretty clear that I had "observed" the wire colors in relation to the connectors, on two separate cars, and that they followed the same pattern: red wire on the car-side connector mated to the black wire on the visor-side connector, and the black wire on the car-side connector mated to the red/black wire on the visor-side connector. The connectors are keyed to only mate in one orientation, of course.

[RickHaleParker]

The Homelink IS chassis ground directly. I knew you got it wrong, tried to spare you the embarrassment.
How see if you can reason out the above.

10/114 is the Homelink.

[BEJinFbk]

Here's the other page that goes with the wiring diagram above.
It looks like the hot lead is pin 1 on the visor. I hope this helps!

2000 S-V70 Homelink Component Locations .pdf

(307.96 KiB) Downloaded 214 times

[SlowLane]

Thank you both. I think I got it from here.

The obvious difference is that the 850 doesn't run the power to the driver's visor through a key-controlled relay, but provides power to it full-time. I'll consider whether I want to go to the trouble of duplicating the S70 relay setup.

[BEJinFbk]

It should draw nada at rest. Killing the battery
won’t be a problem, but I like the idea of securing
the remote in an unattanded car. I ran a line to
the accessory connector and picked up ign there.

Best of Luck!

[RickHaleParker]

Thank you both. I think I got it from here.

The obvious difference is that the 850 doesn't run the power to the driver's visor through a key-controlled relay, but provides power to it full-time. I'll consider whether I want to go to the trouble of duplicating the S70 relay setup.

The S70 relay is for security, a thief cannot get in your car and use the homelink to get in your home.
You could reroute the postive to a switched +12V, instead of installing another relay.

[SlowLane]

The S70 relay is for security, a thief cannot get in your car and use the homelink to get in your home.
You could reroute the postive to a switched +12V, instead of installing another relay.

Yes, that's pretty much what I was thinking of doing. Leveraging an existing switched source.

Funny though, the Homelink in my S80 works fine without needing the key, so it seems that Volvo vacillated on the security issue. Doesn't matter. The S80 lives in the garage. The 850 is out in the elements.

[BEJinFbk]

There’s a factory power point for accessories clipped to
the steering column that gives you access to a number of
different feeds. Just for aftermarket gadgets. Very thoughtful.

There are plenty of posts about it here. If no one
beats me to it, I’ll throw up some info this evening.