Have problem with intermittent speedometer and odometer. 85 300SD. Hit a bump. Both stop functioning. Hit another bump, both might start working. Don't know if it is the speedometer, a connection, the cable, or something in the transmission.

Trying to find the upper end of the Speedometer Impulse Sensor. I think the trans end is in these pictures below. But the other end is where?
Also, there is a round black object behind the gas pedal. What is it? Thanks.

Cannot find on Pelican parts but saw this post
http://www.peachparts.com/shopforum/diesel-discussion/274564-84-300sd-speedometer.html

and this other listing.
Mercedes W123 W124 W126 W201 Beru Speedometer Impulse Sender 010 542 22 17 | eBay

or this picture
http://www.everythingbenz.com/prodimg.php?src=http://img.eautopartscatalog.com/live/W01331615020BER.JPG&h=200&partnum=0105422217

Some pictures of my vehicle
1 I think this is Trans end of Speedometer Impulse Sensor

2 same sensor

3 Behind instrument cluster

4 Behind of instrument cluster

5 Back of speedometer

Attached Thumbnails

         

Also found this black round object with cable behind gas pedal. Screwdriver points to it. What is it? Thanks.

Attached Thumbnails

 

picture1 post 2:round black object is your kickdown switch (operates a solenoid in the transmission)
picture 5 post 1: four posts exposed are for the temperature display

your other symptoms are indicative of an intermittent connection as both the odometer and speedometer are operated by electric signal from the transmission tailshaft housing
picture 2 post1

That would be your kick down switch for the tranny.

I also have 85 sd and the guys here helped a lot with mine. Pull all your wires out of the cluster and look over carefully then clean ends and reattach, also look at the ground carefully.
My problem came from the fuses,the old fuse (#8 )with aluminum strip it was burnt off at the very tip so when I looked at or rotated with finger all looked well so until I pulled it I had non working dash.

So I went to NAPA bought all new problem solved.

Hope this helps
greazer2b