Electrical Help please! Bypassing the memory circuit in 2002

[Mdcptman]

Hey all you electrical genius's, I am in way over my skill level. as Usual. lol

As you may have seen from my earlier thread I just scored some awesome tan power Leather bucket seats from a 2002 Lincoln LS.

http://www.ifsja.org/forums/vb/showthre ... t=junkyard

I'm in the process of figuring out the wiring, and that is really not my strong suit. The passenger seat was a no brainer. hook up power and ground and it just works. the drivers seat has the memory circuit however, and that's where the problems lie. It has a computer mounted under the seat, with a bunch of relays, and it also has to communicate with the vehicle's network. I tested the seat when it was still in the car by hooking a batter to the battery terminals in the car. everything worked perfectly. But now that the seat is separated from the vehicle, the only thing that works is the power lumbar. Apparently the power lumbar is not connected to the memory functions.

Ive tried a lot of searches about this subject on various car and hot rod forums, and im not the first one to have this problem, but I cant find a solution. There the 2 main large gauge power/ground wires coming into the harness, and 5-6 small gauge wires. Ill post pics later. The harness comes into the control module under the seat, then goes to the motor position sensors, and also to the switches, from there it gets confusing. Id like to preserve only the basic power functions. it has power up down front of seat pan, power up/down rear of seat pan, everything up/down, forward/backward, and recline.

Since the passenger seat works, Im going to explore using that harness to figure out which wires are essential.

I did read someones solution to this problem using some GM seats where they were able to jumper a few of the little wires, and everything worked.

I'm hoping that one of the amazing people here will be able to tell me an easy fix. Or point me to a good reference that will help me out. I dont mind studying and reading and trying to figure it out, its just that I know so little about this that I barely know where to look.

I cleaned up these seats yesterday and was able to sit in them a little. They are really comfortable, and I cant wait to move on to trying to adapt the mounts and get these in the Jeep.

[haminawag]

Id like to preserve only the basic power functions.

Well you mentioned that there are relays, that's your key to success. Relays use a small voltage or current to switch (on or off) a large votage or current. Those relays will connect directly to the motors, so you can either leave them in place and clip out the rest of the unnecessary circuitry, or you can eliminate everything but the motors, and add your own switches, relays, etc. Personally I would use the existing relays and switches, but the switches may not work in your situation. Anyway it's a simple matter, though tedious, to locate each motors ground wire and both hot wires, it just takes time and a source of 12 Volts that has enough current to power those motors, from there you'll want to use masking tape or some method to mark each wire bundle and each wire, ex: FWD-BKWD, or SEAT BACK-UP, DN, etc.

You'll need to make some wire extentions, some soldering (rosin core solder only) and just do one motor at a time. Basically you just have to get rid of everything you dont want, the memory module, etc., but just keep it simple and don't rush it and you'll get it done.

[Mdcptman]

Here is the control module, I think those are relays soldered in there. the black rectangles?



bottom of the Drivers seat



Bottom of the passenger seat. Much simpler



Connectors coming into the seat

[tgreese]

I'm going to write as if I really know what this is doing ... realize that some guesswork is involved.

Yes, those should be relays that control the motors. The board switches the coils on the relays, and the relay contacts power the motors. The number of relays should match the number of motors. You should be able to trace from the relay contacts to the motors. Likely the motors have three wires, a common and one for each direction.

The first thing I would do is try to determine which input wire or wires are the power feed, and which is the ground. The system may ground through the seat frame. The large diameter red wire is the most likely power wire. I would try to relate the power wire to the motor relays and the wires to each motor.

It looks like three motors and four relays, which is a little puzzling. If the top/outer motor is the lumbar support, and not controlled by the board, that would be more a more sensible 4 relays and 2 motors = one relay for each direction on each motor.

I think you won't figure out the computerized control without a lot of time or the engineering documents. My goal would be to make the motors run manually from some toggle switches. If you can power up the seat, try activating each of the motors using the relays. Realize that it is very easy to let the magic blue smoke out of such electronics components by connecting power to the wrong point and so forth.

You could get paper and pencil and trace out everything from the relays to the motors. It may make obvious sense depicted that way. Then, you could substitute generic relays for the relays on the board and drive the motors manually.

Hope this gives you some ideas about how to proceed.

[Mdcptman]

Thanks for the help Tim, The motors have only 2 wires. When I apply 12v to one side and ground to the other, the motor moves. If I reverse polarity, the motor moves the other way. So Im guessing the switch reverses polarity, and the relays get the low power signal from the switch and supply high power to move the motor. If i cant figure it out any other way, I may try to take the switch output and wire up some bosch relays. (as if I know how to do that!) I like your idea of trying to trace the board to see where things go. There is a fourth motor for recline. So 4 motors, four relays. You just cant see it in the views Ive given you. Sorry. There is actually another motor in the back for power lumbar, but it has a whole separate and simple circuit that has larger gauge wires running directly to it.

[Mdcptman]

For those who are interested, I finally figured it out!

Let me start by saying that I am pretty ignorant of electrical stuff. Electricity and I have an understanding: I leave it alone, and it doesn't kill me. This has worked pretty well for me so far. Unfortunately, I needed to figure out how to wire these seats, so I had to break our agreement. I hope Electricity understands.

Anyway....

The original issue was that I needed to be able to bypass the memory circuit for the drivers side seat controls. The passenger side did not have memory, and worked just by hooking up the power and ground. the switch went directly to the motor with large gauge wire, and worked well.

When I tried to attach the drivers side main power leads to power and ground, nothing happened. The drivers side switch has much smaller wires coming out of it leading to a seat control module that had four relays. (Pics are above.) I was able to find some portions of the wiring diagrams for the seat switches, but it didn't give me a pin out of the switch. It did give a pin out of the connecter the plugs into the control module, and I was able to figure out which pin did what.

Now realize, that before I started, I didn't really know how to use all the functions of my multimeter. I didn't know what a relay really did, or how to wire it up. I had only a very basic idea of how to read the wiring diagrams.

Basically, I was screwed. Again.

Thanks to advice from here, about a month of research of Utube videos, Internet searches for wiring diagrams, and a lot of trial and error that sometimes involved smoking wires, I have finally figured it out, and the actual solution was so simple, it makes me want to cry.


The orange/white wire is listed as "Reference voltage" in the pinout. The Brown wire is listed as ground. So I figured that those supply voltage to to the switch, so it can activate the relays and they in turn supply power to the motors. The switch reverses polarity so that the motor turns clockwise or counterclockwise. So I applied 12V+ and ground to the large wires coming into the main seat harness, and jumpered power and ground to the 2 small wires in the picture, and Bazinga! The relays clicked, and the seat motors turned happily in either direction.




After doing my happy dance, I happened to look at the cluster of wires coming into the module, and noticed that there was a brown and an orange/white going INTO the module.....Hmmmm.... I traced these back to the cluster of wires coming into the seat, and found that although they changed colors at the connector, (WHY!? ) they were part of the bundle of wires coming from the vehicle to the seats. I wired them to their respective polarities of the main wires supplying voltage and ground, and it worked. it just worked. so simple. so clean. so maddeningly easy.

This was all I had to do all along.


While Im really excited and gratified by all the new knowledge I have acquired during all of this, I sure hope this info saves someone else from the trouble I had to go through.

Now I hafta figure out how to mount the seats in the GW. Ill start a new thread as I get into that....

[tgreese]

Congratulations!

1) All good ideas seem simple in retrospect.

2) Learning is a process.

3) You have learned a lot. Your multimeter is a powerful tool. Use it every opportunity you get. Also good for house wiring, small appliance repair, etc.

Learn enough and then you'll want to move up to an oscilloscope.

Good on you!