power seat wiring, 07 mercury marquis

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URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=106383
Printed Date: May 09, 2025 at 12:04 PM

Topic: power seat wiring, 07 mercury marquis

Posted By: dencouch
Subject: power seat wiring, 07 mercury marquis
Date Posted: July 27, 2008 at 1:15 AM

I require a review by the pros of this schematic for wiring a power seat to travel forward/reverse. This look okay?
posted_image

Thanks for your effort to help.

Replies:

Posted By: i am an idiot
Date Posted: July 27, 2008 at 2:40 AM

It is too early in the morning to figure your diagram out. Do you have the rocker switch yet? If so how much current is it capable of handling? Following is a diagram using 2 relays, the switch can be any momentary rocker switch, it will only have to handle the current pulled by the coil of the relays. It will last a lot longer than a switch actually supplying power to the motor.

This diagram was initially intended for door locks. Disregard the part about the alarm connections. You only need one switch. It says to Switch(es).

posted_image

Posted By: dencouch
Date Posted: July 27, 2008 at 9:42 AM

Thanks for the help & illustration.

I wish I could tell you what the A rating on the rockers is. I pulled them out of a door panel on a T-bird yesterday because they were DPDT.

I also pirated a fuse & buss box from a Ford Ranger. I kind of fell in love with this unit because it had sockets inside for 5 relays & 4 were already installed. This is what I am having to work with, unfortunately.

I have scavenged a pair of seats that track fwd/reverse, seat back adj, seat front up/dn, and seat rear up/dn.

I am an industrial electrician by trade, but that does not mean that I have got it all figured out when it comes to auto wiring. Amazing how much current a low voltage system takes IRL.

Thanks again.

Posted By: dencouch
Date Posted: July 27, 2008 at 9:51 AM

From my experience out in the field, I am doubting that the rocker switches can carry the current reliably over the long term.

There is always the "great unknown" (ignorance!)... what is the current capacity of a seat motor anyways? And what about the switches? Those puppies are huge!

See where I am?

Dazed & confused & all I want is the seats to work.

Posted By: i am an idiot
Date Posted: July 27, 2008 at 10:05 AM

If you find out how much current the motors draw in a real world situation. With you sitting on the seat as it moves, you may be able to use the switch for maybe the tilt function. You may have to use a meter to verify the operation of the switch you have. Following is a DPDT momentary switch. I have no idea how your switch is layed out, but the picture should give you an idea of how a reversing switch is wired to achieve both directions.

posted_image

Posted By: dencouch
Date Posted: July 27, 2008 at 10:41 AM

Yes, I ohm'd out the switch to verify what I had in my sweaty little hand. I have an amprobe that meters DC current. I will have to check out the current draw with a load on the seat.

From what I see, it appears that I am going to have to rethink my wiring plan and pop for additional relays to remove the load from the rocker switch contacts.

I wish that the components on cars (like the rocker switch!) were labeled with specs so I would not have to post like this for help.

Okay, I am going to omit some of the seat features and double up on the relays. This will remove the load from the rocker switch and put the burden back onto the relays.

Any idea as to what size the fuse protection should be? What about wire size for the load & signal wiring?

Thanks, I appreciate your feedback.

Posted By: dencouch
Date Posted: July 27, 2008 at 12:20 PM

I would like to see a wiring diagram for the power front seats, if itis out there someplace.

This would make my life a whole lot easier.

Thanks.

Posted By: i am an idiot
Date Posted: July 27, 2008 at 2:07 PM

I think a 10 Ga. wire and a 20 amp fuse should more than cover it.

Posted By: i am an idiot
Date Posted: July 27, 2008 at 9:55 PM

Are the switches mounted to the seat?

Posted By: dencouch
Date Posted: July 27, 2008 at 10:38 PM

One switch is, the others were in the door armrests.

On the bottom-outside of both seats is the fwd/rev rocker.

On the door armrest was a multifunction switch resembling a seat profile. This switch would rocker every which way. I should have taken more of the electrics off the car when I had the chance. The wrecking yard sold the car out from under me & all I got was the seats.

Thanks for showing interest in my plight. You have been a great sounding board.

Posted By: i am an idiot
Date Posted: July 27, 2008 at 11:00 PM

You already know that there are 4 motors in the seat. If the rocker switch is for sliding the seat front and rear, chances are it will handle the current of that function. You will have to build 3 sets of the relays for the other functions. There should be 8 wires coming from the seat. 2 go to the rocker switch and 2 to each of the motors. If you find the ones going to the switch you should be able to apply power to one and ground to the other, try the switch, if it moves properly you are set, if it moves backwards, reverse the wires. The other motors will go to the motor out of the relays. Connect and if they move the right direction, leave them. If they move backwards reverse the motor wires.

Posted By: dencouch
Date Posted: July 28, 2008 at 12:07 AM

Thanks, but it seems a bit more complex than that, as I have TWO plugs. Three of the motors go into one plug and the motor of which we just spoke, is wired to the other.

Posted By: i am an idiot
Date Posted: July 28, 2008 at 8:25 AM

The motor on the single plug, does it have only 2 wires?

Posted By: dencouch
Date Posted: July 28, 2008 at 8:31 AM

I wish!

No, one plug is brown & consists of wiring for 3 motors. The other plug seems to be a cross between a data cable & a seat plug. Two of the terminals in the plug are pins that work the seat back and the rest appear as small blades like in a data cable. a mess of them as well!

Posted By: dencouch
Date Posted: July 29, 2008 at 11:22 PM

I found the info i needed at the local library. The schematic does not show relays needed for the seat operation! The switches used on the door panel are wired directly to the seat motors. The multi plug utilizes 4 wires for the seat mounted lumbar support switch and the related compressor motor.

20A fuse is all that is needed.

Thanks for your help with this.