Several years ago, had a new tranny put in my '90 SE. During post repair test drive, noticed that speedometer wasn't working. Took back to the shop and was told to drop off for an afternoon and they would reconnect cable. When I went to pick up later that day, I was told that there was a module on the tranny that the speedo hooked into and that the shop had shipped back the core with that module still attached. Gave me a break on the cost, and I wasn't too concerned as kept GPS in car and used that info. Oldest daughter just turned 16 and I'm looking at passing car down. Seeing that speedometer is MUCH more important to a young driver, would like to get it operational again.

I'm not having any luck finding this "module"...where should I start to fix this?

 

I think that speedometer wire is routed to the right of where the driver places his (her) right foot, behind the carpet panel. See adobe reader page 60 on the wiring diagram below (takes awhile to load) and it is called a Vehicle Speed Sensor.

Search google.com for the following words...

1990 mercedes speed sensor speedometer

Here are the electrical diagrams...
http://www.startekinfo.com/StarTek/o.../126from86.pdf

Mercedes W126 Factory Service Manual here...
Untitled Document

 

Thanks for the info Elektrische!
The electrical diagrams will come in handy I'm sure, but the service manual will let me go to the systems for each vehicle, but when I try to go to specific documents, it says they are not available...no matter which I choose. I will try opening in a different browser and see if that helps!

Not having any luck finding the sensor...most posts lead to ABS sensors or a part that is not compatible with the 126.024...If anyone knows the part# I would be eternally grateful!!

 

Here is the same service manual information on a different site which may work...
Model 126 Maintenance Manual Index

But those do not give part numbers. Might want to go to a Mercedes dealer with your VIN, then they can get the right part.

Or try here...
Index to Mercedes EPC Parts Info and Diagrams | Everything Benz

Or Mercedes Parts diagrams here...
EPC-net Online

 

thanks once again! Those links worked much better! The speedo job has been put on hold as I'm now in the middle of the fuel pump, filter and connecting lines replacement. Oh well...!