passenger seat motor wont allow me to go forward and backward. ordered another motor and it still did not work. has anyone had this happen before.

 

check fuse.

 

checked fuses and none are out.

 

Check the seat switches, if is not that then it probably is the seat memory brain, which is the black box with a zillion plug and wire connected to it. Both are expensive. You get to it by removing the 2 screws located at the botton corners of the botton seat cushions and pulling up the seat. Then it is easily assessable. The unit is "sealed" with a screw which hold both covers. Check for corrosion and "burns" around plugs and printed boards. If there is you need a new one. About 1000.
If you are single, get it fixed. If you are married, rotate the motor shafts until you get the position you want and leave it alone, unless you have a 1000 to burn.
Good luck

 

same thing happened on my 1990 300SL, I swapped over door switch and black box with drivers side as a test and deduced it was the black box on passenger side that was malfunctioning..

I was fortunate and found one on eBay (after 18mths of searching) and only paid £100 (GBP) from a private seller in germany.

Installed the new black box and all works well.

The original one was water logged, either the roof had been left open and rain got in or water leak from bad hard top seal was the culprit. (previous owner)

My advice, search worldwide on ebay and other web sites, as these are very rare items to purchase second hand.

Make sure Part numbers are identical when purchasing too !!!

best of luck

Simon

England

1990 SL 24v