What is this?
 

Can anyone tell me what the black box is on the back of the speedo is in this picture?? This is off of an 82 300D. Could it be the speed sensor for the CC? Thanks in advance Tom 82 300D

no pic

Sorry was having trouble getting it uploaded. Take a look now. Thanks Tom

It is the speed sensor for the Cruise Control (CC).

Called a transducer.

Testing Speed sensor/ What is this?
 

AHHH... Do they go bad and mess with the CC?? Tom


Is there a way to test the speed sensor? Or how often do they go bad? Thanks Tom

bump....

Its an electromagnetic induction pickup, there really isn't anything that can go wrong with it.

Its far more likely that the cruise control amplifier is at fault.

Forced, thanks for the info. Just checking to make sure i have coverd all the base's before I bite the bullet. I resoldered my orig. amp. which was interm. and then quit alltogether(no luck) then tryed 2 USED amps. and 2 used actuators with no luck. Soo I guess I need to try a new amp. I have all good signals from the switch. Thanks again. Tom 82 300D

I remember reading a thread a few years back discussing installing an aftermarket CC using the original stalk. It might be a more reliable alternative to the trouble plagued OEM set up.

Me too....I am probably going to finally attempt this in the spring (or when it finally gets warmer)....I've had an aftermarket cruise setup in a box forever. Not sure if I will mess with the stock stalk though, the system I got comes with a tiny little switch that'd be no big deal to mount next to the headlight switch or something....then I can restore the original system someday if I want. I'm also going to look for a way to put a little green "Cruise" light in one of the spaces in the cluster....if the system would support such a thing.

HMMM... Aftermarket Cruise?? What is it or do you have any other info on it? Thanks Tom

Rostra makes a good aftermarket unit, I've used them (not on Mercedes).

Yes, Rostra! That's the one I read about being used successfully in a Mercedes.