Seat function issue 85SD with 89SE seat bases.

[Clemson88]

Left front seat...The 89 seats electrical schematic shows the wiring at the seats to be different than the drawings on the 85 body so I opened the seat connector on the body wiring and moved the wires to match the 89 drawings.

The headrest button moves the front of the base up and down. The main button for the base moves the backrest back and forth. The other switch functions do nothing.

I've tried moving the wires in the connector to suit both model drawings and nothing seems to make the seat move as it should. Some of the motors run but the seat body doesn't respond.

The right front switch does nothing. I have no idea what to do with this. The seats worked perfectly in the 89 body.

Does anyone have any advise on what I should do?

[barry12345]

Got a friend with more electrical experience? I would determine what wire serves what purpose in both ends first. Chart that and it may be easier to rewire.


It strikes me that the actual seat controls are in the seat. So if power is fed in to them as intended it should work. Now if the newer seat has some form of memory set up. It could get a little complex.

[Clemson88]

There are differences between the 85 and 89 bodies but I am positive I have tried the seat with the wiring configured correctly.

When I had the seats on the table I used the leads from the motors to move it back and forth, up and down to disassemble it for stripping, leather softening and shooting the SEM Surecoat on them.

I adjusted them to make it easy to install without using needing to put the battery back on the car.

I'm guessing I screwed them up in assembly or something. I'll pull them out and check all the motor functions tomorrow. Starting from scratch.

[barry12345]

I suspect without knowing that the memory function is not in the seats. You may have to run some similar new power system to the seats. If you made them work on the bench. You probably already know what is needed.


I have to also mention that I have never played around with power seats. If the 85 had memory power seats it might take some real effort to make the non memory seats work as memory seats. It may be almost impossible or if possible very difficult.

[Clemson88]

Originally Posted by barry12345

I suspect without knowing that the memory function is not in the seats. You may have to run some similar new power system to the seats. If you made them work on the bench. You probably already know what is needed.


I have to also mention that I have never played around with power seats. If the 85 had memory power seats it might take some real effort to make the non memory seats work as memory seats. It may be almost impossible or if possible very difficult.

Both models, 85 and 89 had memory switches on the doors, memory modules on the seats. Neither had the heat or telescoping steering functions.

The connectors from the modules out to the motors seemed to be impossible to connect wrong but somehow, someway I have once again messed up something with appeared dumbask proof.

I appreciate the responses, I just needed someone to back me off the ledge.

Thanks

[Diseasel300]

Are you sure about the '85 having memory? I thought that showed up in '86 with the W124 and Gen II W126.

[Clemson88]

the body is wired for memory with the black/red, black/brown and black/green wires. The drawings show it too. I know the seat has the function because it has a 14 pic connector which is exactly how many wires the body harness includes.

If the wiring harness, switch and seat is set up for memory and the constant power of a .75mm red/white wire is there and hooked to the right pole on the four pole power hookup on the seat module it seems like that's all you need to make it work.

I'm positive this wiring came original in this body. Perhaps it was a late 85 model. It is a gasser being a 380SE body.

[Clemson88]

Anyone have any ideas about testing a seat control without power such as continuity through the control input to where the motor wiring connectors go?

[Junkman]

Originally Posted by Diseasel300

Are you sure about the '85 having memory? I thought that showed up in '86 with the W124 and Gen II W126.

My 85SD with MBTex has a two-position memory function. Those seats are different from the 84 which has dry rotted leather. I haven't compared yet with the seats from a later than 85 gasser 126 that are sitting on the shop floor.


The connectors on the 84 car side don't match physically the connectors on the later seats. So, there are 2 issues - 1) do the connectors match & 2) does the wiring match?


There seem to be differences between 84 and 85 models with 85 being the change year. I don't know when the next change was perhaps in 86 when the 617 was out.

[Clemson88]

I have an 85 SE body in which I have installed an 84SD engine/trans. I am trying to get seats from an 89SE to work in the 85 body.

The 85 body has a 14 pin connector at the left seat which plugs into the seat control mod.

The 89 seats are set up for 14 pin connectors at the seat module.

I disposed of the mechanical parts of the 85 seats.

The wiring colors of both according to the FSM drawings are identical other than seat memory wires. The difference is the base color on the memory wiring. One is black/green, black/red and black/brown.

The other is brown/green, brown/red and brown/black.

I have tried wiring configurations like in the 1985 FMS drawings and the 1989 FMS drawings.

I have removed the seat and used the connectors to the motors to remove the base/backrest from the rack assembly. I'm calling the motor assembly a rack because I have no idea what it's properly called.

I intend to put that rack back in the body where it suppose to go, check the power wiring then hook it to the rack.

I can make a simple switch which will allow me to chart which pins move what. That sounds good in my head, I hope it coherent to the reader.

While I'm posting, I suspect the control modules are bad on both seat modules so if anyone has a pair from an 86-91 w126 they want to sell contact me.