Finally power seat problem solved
 

Just wanted to update everyone.

I just got my car back and now all power seat functions work. In my case, the problem was the relay under the seat. This is an easy fix as long as you can still remove the seat. The mechanic had a hard time getting to those bolts and charged me accordingly ($$$$$). Damn it. That's o.k. I had other misc work done too, and I'm satisfied.

Anyway for anyone with similiar problems, follow these troubleshooting tips:
1. Don't play with the switch if you know it's not working properly
2. Don't move the seat all the way forward/backward (it'll block the bolts holding the seat), you may have to take the seat out to check the relay, motors, cable, etc. under the seat.
3. First check the switch (most probable cause of the problem 90% of the time....according to my mechanic. This is an easy 2 min DIY job)
4. Remove the seat and check the relay
5. Elimininate other causes ie. cable, motors, etc.


Thanks to everyone who tried to guide me in the right direction.

Unfortunately I could not fix this problem myself. I became frustrated and gave up when I could not remove the 2 rear bolts...it was nearly impossible to get at. Like a dumb @ss I kept messing with the switch and the seat got stuck all the way back, hence blocking the rear bolts.

Hopefully my experience will save someone $$$$$ and lots of headaches.

jrmd01@yahoo.com

Do you have details on which relay was replaced? Is the part number on the invoice?

Sorry the part number is not listed on the receipt
 

Sorry, the part number is not listed on the receipt. It was a used one so that's probably why he did not list it. He just listed it as "replaced seat relay w/used one".

If you look under the seat, you can see it. It's kind of big...rough estimate 6"X8". It looks like a flat rectangular black plastic box. According the the mechanic, a new one is apporx $600. He sold me a used one for $100. I should have asked him for the old part, but I have no use for it, so I never bothered.

Everyone, please check your switch first because 90% of the time this is the culprit (2 min DIY job). For the remaining 10%....good luck....hopefully it's something as simple as mine --- the relay.

jrmd01@yahoo.com

part # of seat relay
 

I went back to the mechanic to pick up the old relay. The part number written on the relay is 124 820 00 26

Hope that help.

This thread is done.


jrmd01@yahoo.com

Seat switch fixed at last!
 

When I bought my 90 300D sedan in 1999, the seat would not always slide back. I thought it was a problem with the seat motor and therefore did not mess with it. A mechanic told me I would have to remove the entire door panel to mess with the switch. I didn't want to pay him $300 for three hour's work, plus parts, and I was too lazy to mess with it.

There are two kinds of switches: the one with a memory has tewo small 1 and 2 buttons on it. Mine was the forgetful type, which is cheaper.

Then my neighbor drove the car for a while and in a totally unrelated incident the front of the seat was tilted all the way down and would not rise up at all. The switch seemed loose as well. So I decided that perhaps the entire problem was in the switch.

So eventually I finally got around to checking this forum. jmcd01 in Hawall discussed how he actually removed the switch, took it apart, cleaned the contacts and put it back together. His instructions were excellent.

The only problem was that three of the teensy ball bearings had somehow vanished. I cleaned all the contacts with a small Dremel grinder. The contacts are brass thingies about 3.8" wide in the shape of a vee with a flat spot on the bottom. The contact points are the flat part of the vee and the two little blobs on the underside of the end of each wing. These rock back and forth under a combination of ball bearing-spring-ball bearing. There are four switches: the two with the white inserts are for the seat back and the center of the seat, where it controls the back and forth movement of the seat. Two other plastic switches don't have a white insert and go on each side of the seat slider. All four of these (four plastic switches, eight springs and 16 teensy ball bearings will all fall out when you open the silly thing. A brass axle the diameter of an old thin ballpoint pen refill runs through the hole in each of these four plastic switches.

I was short one axle and three ball bearings and could not locate any ball bearings anywhere, so I gave up and bought one at Finish Line here in Miami for $82 ($87 with the FL state sales tax). They are a good local place to get filters and mats and such. If you try to find them in the phone book, they had a fight with Ma Yellow Pages and after three years of her posting the wrong address Finishline removed their ads. But they are open Mon thru Sat from 9 to 5:30 at 5760 SW 8th Street, 305 266 9687, 800 842 7851, in the event you need a Hengst of Mann filter for $6.00 right away.

I was thinking that there might be a way to magnetize the top ball bearings to get them to stick atop their springs. I was about to go out ansd get the recommended diaelectric grease when I decided than my lack of ball bearings would prevent me from fixing the thing. I guess the missing balls need to be inside the door somewhere, but I was too lazy to open it up.


The headrest switch is more polite and might not come loose. To clean it, just pull it upwards and clean the inside of the vee switch and the two contacts on the outside of the wings of the vee.

I am posting this in the event that it might make it easier for someone else to fix their seat. It is really great to be able to move it without fiddling with it for a couple of minutes to get it forward or back.

Many thanks to jmcg01.

relay
 

How did you test the motors? Can the relay be tested?

Well I know this is a very old thread but jrdm01's posts did indeed help me diagnose the exact same problem that he had. My drivers side front seat won't go forward or back but does everything else. I too hear a click under the seat when I press the appropriate button so it must be the relay. Luckly my seat isn't all the way back and I can tilt the seat and the backrest forward to expose the back bolts. I just applied some liquid wrench on one of them as it is pretty rusty so we'll see what happens when I get the seat out. Hopefully I'll be able to find a cheap used relay to replace the one that is there.

I just wonder if it's still possible it could be the wiring going from the relay to the motor since I hear a click, but then jrdm01 heard a click to and the relay had to be replaced. I am not even sure how to test the wire going from the relay to the motor.

Any thoughts anyone?