cruise control surges
 

84 300D Turbo

as stated, cruise control is not right- it surges at all speeds erratically-

is this an actuator problem or the "cruise control brain" under the dash problem?

Amp' problem.


.

I respectfully disagree; this can also be caused by a jerky actuator (internal problems) or linkage issues. I have two spare actuators, and only one of them is "jerky". I'm going to try to fix it this winter. I suspect that the "wiper" for the position feedback is worn/dirty/lost its spring or there is a lubrication issue.

so of it is an amp prob. what contacts should I check- and how do I test the contacts while cc is on (if im driving and i put it on) cuz it dont work standing still.....

if it is an actuator problem, I will go to the yard and pull another- test to see if that fixes the problem- however I would like to be positive that is the issue before I buy a junk part I cant return

Which begs the question- how can I find out where the problem is?

Try this link. I had a similar problem. The GDL website is good cause it shows you how to test all the cruise parts. Before I went through the tests on the gdl website I actually called the guy, described the issue, and they virtually assured me it was the amp. Told me not to even bother testing the other stuff. Popped in a used amp and problem solved.

http://www.peachparts.com/shopforum/diesel-discussion/123036-cruise-control-repair-articles-post883130.html#post883130

In think it can also be caused by bad speedo cable--is the needle unsteady?

Have one W124 that has unsteady needle when cold but when warm needle is fine. Cruise behaviour mimics this, i.e is fine when needle is steady.

The speedo cable is a little twitchy from 0-15 mph, after that it is fine- the CC is surgy all the time-lower speeds more than higher- worst is at 45-55mph, but still noticable at 70.

Thanks for the link. I'll look into that ASAP.

welcome to mb shop dubmutant

check the archives first by using the search feature...if it's happened to you you can bet it's happened to someone else.

your cruise control problem is your amplifier. you can look for a broken solder connection or buy another one.

i found 3 pages of cruise control surge threads...http://www.peachparts.com/shopforum/search.php?searchid=860113