Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 02-13-2000, 12:21 PM
walt
Guest
 
Posts: n/a
I have a '77 240D which I purchased new and have kept well maintained.

I am having a problem with the cruise control. When engaged, it will not maintain constant speed. It surges and sometimes disengages.

What is the normal cause of this problem? I would like to repair it myself.
Reply With Quote
  #2  
Old 02-13-2000, 03:01 PM
Luke's Avatar
-.- .-.. .- - - .-
 
Join Date: Aug 1999
Location: Saint Helena, CA
Posts: 166
Walt, did repairing the vacuum leak also cure your cruise control issue? If wiser folk feel it is the amp, then I can help you with that, if you are, or know someone who is, handy with a soldering iron.

Regards - Luke
'78 300D
Reply With Quote
  #3  
Old 02-17-2000, 04:18 PM
walt
Guest
 
Posts: n/a
The vacuum fix did not affect the cruise. I am open to suggestions.
Reply With Quote
  #4  
Old 02-17-2000, 07:26 PM
Luke's Avatar
-.- .-.. .- - - .-
 
Join Date: Aug 1999
Location: Saint Helena, CA
Posts: 166
Walt, this approach assumes that the cruise control amp is faulty, and not the vacuum servo.
The 10 pin analog cruise amp (MB diesels to about 1981, I think) has three very common failure causes: 1] The LM-2901 comparator IC chip. 2] The dual gate N-channel FET. 3] Failed solder joints / broken PC traces. 4] Some odd combination of all of the above. The above parts are about three bucks at Radio Shack, but are probably cheaper elsewhere.

Pull the amp out to a clean bench, and take a look for failed solder connections or cracks. Retouch suspect ones. While you, or your electronic savvy helper, are in there replace the two active components I mentioned. I repaired my amp, and those of four local friends with this method, and we're all cruise control positive. Another required a few days, and some rather expensive test equipment I have at hand. If you draw the short straw, and get stuck with that kind of failure, then an exchange box is your best bet. I think they run around $200. Inquire first with our hosts at Partshop, since they're such good sports.

Good luck,

Luke - An engineer who drives to work everyday in his '78 300D

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cruise control problem and a solution 81Wagon Diesel Discussion 3 03-15-2004 05:58 PM
300E lamp bulb warning light intermittent problem / cruise control JFAZ Tech Help 6 11-15-2002 01:52 PM
Cruise control switch problem??? MikeTangas Tech Help 3 07-06-2002 03:07 AM
Cruise Control stops at 60MPH Austin814 Featured Cars 2 01-13-2002 12:02 PM
560SL Cruise Control Problem Bob Cavazos Tech Help 1 04-16-1999 02:26 PM



All times are GMT -4. The time now is 12:41 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page