Cruise Control Supposedly never worked right on my car...????
 

The gentleman I bought my car off of said that the cruise control never worked properly off of the lot. He said it's been in numerous times for the cruise control, and still it never worked consistantly. Well it's never worked for me, not even once. I looked at the throttle on the engine and the bar from the cruise control unit to the throttle wasn't secure and it didn't even fit on the cruise control unit. After I had her in at mercedes (not for cruise control work) I noticed while charging my AC that the bar was now completely gone, it's almost like they said "oh you don't need this, it doesn't work anyway." which makes me mad! I would like to have cruise control, I use it a lot in my jeep. What would a complete cruise control system replacement cost (parts labor, etc)? OR what could the problem be, other than that bar not being there.

The cruise control amps (box under the dash) is the most common failure. They are ~$150 for a rebuilt. Some folks try "resoldering" the old ones, but that seems to work better on older ones (W116, W123) and not so much on the newer ones (W124, W201, etc). Your actuator (on the engine) could be bad as well but it's a lot less likely. The amp is pretty fragile electrically. All of my cars either have a rebuilt unit installed or need one!

How do I determine it is definately the amp and not that actuator? I don't want to start tearing my car apart and come to find out that it's not what needed done?

Is that arm that goes between the actuator and the throttle easy to find and expensive? Thanks for the reply, man.

I don't know of a way to test, other than to get a rebuilt amp, install it, and see if it works. If not, then it's most likely the actuator. I'm assuming you've checked the fuses, electrical connections, etc. I'm not familiar with the linkages on your car specifically, but if it's anything like my cars, the little link arm (with a ball socket on each end) is available from any dealer (or online MB parts place) relatively cheap.


HTH,

This site will help you with the neccessary test (amp. draw) for the actuator. http://gdl-online.com/testproc.html

Hey thanks a lot! When I get the time, I will try those tests and possibly contact them. Thanks again guys!

Hi all
Looking for diagnostic procedure to troubleshoot cruise control problem. Did a search and came up with this thread. Tried the "gdl" site mentioned above, but I can not get it. Has it moved? Any other sites that provide a test procedure?
Or maybe you can help me....
Recently bought a 82 300SD. The po said the cruise did not work, and gave me another amp that he thought did work. When driving back from Florida to Wisconsin, it did not work until about Illinois. The cruise worked for about a hundred miles then stopped working again. Today, a "warm" day in Wisconsin, I changed out the amp. Still does not work. It is possible the replacement amp was not good either, but before I buy a new/rebuilt unit, I'd like to be sure.
Can anybody provide some troubleshooting advice?
Thank You
Fred Konchan

It's www.gdl-online.com. The company name is General Development Labratories. I just tried to pull it up directly and through Google and I couldn't. They must be having server problems. They are listed on Google. They rebuilt amps from both my cars and both work great. There's also some helpful stuff on the website about testing the acuator but it takes some looking, it's not the best website.