996 Seats in a 928 --Help!

[CaseyH]

I have already installed my 8-way power 996 seats in my 1981 928. I'm not sure of the exact year of the seats, but I know they are 2002+. At this point I do not care about hooking up the heat, I just want to hook up the power. Hooking up the power on the passenger seat was a piece of cake. The driver's side is much more difficult. The power wires are connected through the memory control unit. I've been told that in order to hook up the power for the driver's seat I need to buy new seat switches that are not made for seats with memory. I am hoping that I can possibly rewire the driver's seat myself without buying new switches. The problem is, I'm not sure where to start. Can anybody help me with the wiring and let me know what exactly I need to do? The harness in the 928 is very simple, it has one positive wire and one negative wire. I do not want to hook up the memory.

Thanks,

Casey

Edited March 12, 2007 by CaseyH

[Tool Pants]

I don't know where to start but maybe this will help.

http://www.renntech.org/forums/index.php?showtopic=12780

[CaseyH]

I don't know where to start but maybe this will help.

http://www.renntech.org/forums/index.php?showtopic=12780

Thanks, I did see that, but that procedure is slightly different. He put more simple sport seats into a car with memory, and I want to put more complicated seats into a car with no memory. I don't care about hooking up memory or heat, just power. I can't hook up the power on the drivers side as easily as I could on the passenger side because there aren't any obvious power wires. On the passenger side, there is one red and one brown wire--both thicker and obviously the power wires. On the drivers seat, there are separate wires that run from each motor and wires that run from the switches. I will take pictures later tonight for those of you that do not know what I am talking about.

Thanks again,

Casey

[CaseyH]

All of these harnesses were connected to the memory control unit. As you can see, there aren't any obvious connections for the power. The black and white wires on the LS, HV, and HH harnesses are slightly thicker than the red and brown wires. Does anybody have any ideas?

Thanks

I think these go to the switches?

These go to the motors.

Edited March 15, 2007 by CaseyH

[CaseyH]

Does anybody have any ideas? I would really like to have the seat in this weekend, but if I can't figure out this wiring I won't be getting it in any time soon. I haven't driven my car in over 3 months. I would just install the seat and not worry about hooking up the power but the seat is power reclined all the way forward. Any help is appreciated.

Thanks

[Loren]

All go to motor control.

HH is up and down of either the front or rear of the seat motor.

HV is up and down of either the front or rear of the seat (opposite of HH) motor.

LS is Longitudinal adjust motor.

These are to the motors but they are normally controlled by the seat memory controller so I don't know the signals they get.

Black and white on all three go directly to the motors.

In the top pic Grey/Red, Grey, Grey/Green, and Grey Black go to the Backrest Angle adjust motor. Grey/Green, and Grey Black go directly to the motor.

[CaseyH]

I'm not sure why I was told I needed to buy new seat switches then. I'm not very experienced when it comes to this electrical stuff. Is there a way to hook up the power on the seat to my very simple harness in my car? Essentially I just want to make the wiring on the drivers seat the same as the wiring on the passenger seat. I only need to hook up the power.

Thanks,

Casey

[Loren]

Since it works ... how is the passenger seat wired? (wire colors please)

[CaseyH]

I don't have my camera available right now, otherwise I'd take some new pictures of the wiring on the passenger side. So, I'll see how well I can explain this. The picture of the harness below is actually of the driver's seat main harness, but I altered the picture to reflect the passenger harness. The passenger harness has two extra, thicker wires--one red and one brown. I simply cut these red and brown wires so they are no longer connected to the harness. Then, I spliced them together with the red and brown wires in my car.

It's as simple as that, the seat functions now.

Thanks

[k996c4s]

I don't have my camera available right now, otherwise I'd take some new pictures of the wiring on the passenger side. So, I'll see how well I can explain this. The picture of the harness below is actually of the driver's seat main harness, but I altered the picture to reflect the passenger harness. The passenger harness has two extra, thicker wires--one red and one brown. I simply cut these red and brown wires so they are no longer connected to the harness. Then, I spliced them together with the red and brown wires in my car.

It's as simple as that, the seat functions now.

Thanks

There's a module under the front of the drivers seat that controls everything. You identified the motor wires in your photos, but not the switch wires. If yours is the same as mine, the switch wires are connected to a white/blue/black plug that has nine contacts. The bad news is that from what I can tell, the switches provide a contact to the PC board that with logic and relays controls the motor and its polarity. The switch wires on the passenger side carry voltage to the motor and are fairly heavy gauge. The switch wires on the drivers side are much thinner, and don't appear to be designed to pass the amperage required to run a motor.

To explain it further, I'll number the contacts: (This is the way they'll appear when you remove the switch plug)

1 2 3

4 5 6

7 8 9

I checked the contacts for continuity and found the following. (Just a few for example) These are the pins that are connected when the stated button is pressed:

Forward: 2/9

Back: 2/8

Seat back tilt back: 3/8

Seat back tilt forward: 3/9

I'll check it out further tomorrow and let you know if I find anything that can help.

[k996c4s]

I don't have my camera available right now, otherwise I'd take some new pictures of the wiring on the passenger side. So, I'll see how well I can explain this. The picture of the harness below is actually of the driver's seat main harness, but I altered the picture to reflect the passenger harness. The passenger harness has two extra, thicker wires--one red and one brown. I simply cut these red and brown wires so they are no longer connected to the harness. Then, I spliced them together with the red and brown wires in my car.

It's as simple as that, the seat functions now.

Thanks

There's a module under the front of the drivers seat that controls everything. You identified the motor wires in your photos, but not the switch wires. If yours is the same as mine, the switch wires are connected to a white/blue/black plug that has nine contacts. The bad news is that from what I can tell, the switches provide a contact to the PC board that with logic and relays controls the motor and its polarity. The switch wires on the passenger side carry voltage to the motor and are fairly heavy gauge. The switch wires on the drivers side are much thinner, and don't appear to be designed to pass the amperage required to run a motor.

To explain it further, I'll number the contacts: (This is the way they'll appear when you remove the switch plug)

1 2 3

4 5 6

7 8 9

I checked the contacts for continuity and found the following. (Just a few for example) These are the pins that are connected when the stated button is pressed:

Forward: 2/9

Back: 2/8

Seat back tilt back: 3/8

Seat back tilt forward: 3/9

I'll check it out further tomorrow and let you know if I find anything that can help.

After lots of effort, I can't figure a way to make it work with the existing switches. The same type of switch setup as the passenger side would work, and I once saw one available on ebay in the past. Maybe you could get the switch assembly from someone like LA Porsche Dismantler. I expect it would have to come from a seat that is otherwise not sellable.

If you want to do the work without disassembling or installing the stock seat switches, you could install your own. Just an idea if you're interested, you could use the bracket under the front of the seat to install a small plate to hold switches. The plate (painted flat black) and the switches wouldn't be visible, but would be easily accessible. This would be very easy to wire. You already know where the motor wires are. The 12vdc and the motor wires can be connected to the switch with ease. If you want to try it, you'll need dual pole, dual throw switches, with center off. You want the momentary on-off-on type that returns to "off" when released. Set up the switch as a reversing type by reversing the polarity on one set of terminals. This will enable the motor to move in one direction when pushed on one side, and the other direction when pushed the other way. I attached a picture of a switch you might use.

I don't think this is a great solution, but not knowing what you want, I thought I'd throw it out there.

Good luck.

[CaseyH]

I appreciate all of your help, but the first thing I noticed is that...I don't seem to have this plug you are talking about. The only plugs that I can see underneath my seat are the ones I posted in the photos earlier, and the main harness I posted a few posts above. Maybe you can tell me where this thing is at, but I don't see it. What year is your car?

Does anybody have a diagram for the memory control box? I would also like to know what each spot on the box controls what.

Is it possible to maybe run some new wires for the seat?

Right now, until I figure this out I am just going to run power to each motor and get the seat where I want and then install it. Since I am the only one driving my car I shouldn't have to adjust it...however, I would prefer to have the seat work.

Thanks

[k996c4s]

I just noticed that in your "switches" photo, it appears that the small black and blue plug may be the switch plug. Not the plug and wires you point to, but the one to the right of it. Mine has a third section that's white, but it is for the lumbar control. I can't tell from the picture, but if the black and blue plug has a total of six connections, then I'm pretty sure it's your switch plug. If you have a VOM you can confirm it by following the pin guide I gave and check continuity when pushing the switch. Regardless, per my previous post, these switches can't control the seat like the passenger side. You need to either replace the seat switches and wiring or add new switches.