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Premium Member
1988 300 SE
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47 Posts
Discussion Starter #1
I have been reading several forums on the common problem with the older model MB cruse control. I understand that 9 times out of 10 it is the amplifer, and the electical connections need to be resoldering. I just wanted to know what the symptons were. At times when I am driving the cruse just drops out. and sometimes will not engauge. There are times that it stays on for miles. and other times it will not engage at all. Dose this sound like the Amplifer? And the common cause is loose connections which need to be resoldered? This is in a 1988 300 SE. Thanks Love the forum.....[B)]
 

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Moderator
1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
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4,292 Posts
Hi LordNikonXTC,

Welcome to benzworld.

You'll find the W126 forum pretty lively & if you do a Search for something pertaining to your car the 126 forum will likely get more results.

You are correct the Cruise Amp has a reputation for solder joints failing after all the years... Zillions of articles on them... well quite a few actually.

Here's a good one that will save you some money. If this were my car, I'd do this first.

http://www.mindspring.com/~houlihan/merc/cruise.htm

[:)] MBL
 

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Premium Member
1988 300 SE
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47 Posts
Discussion Starter #3
[8D]I would like to thank everyone who gave me advice on repairing my Cruse Control Amplifier. I was a little scared at first plus getting my 6 foot 280 lbs under the dash board was not an easy. After removing the component, I removed the card from the casing and proceeded to resordier all of the connections. When you look at it you will not think that something may be loose. It look new to me but then again my car is in excellent shape. By the way no one told me about putting the screw back in … it was a nightmare. Replaced, tested, everything works fine. Thanks again to all who responded and to the Forum. I have another quagmire for you but not just yet……. Here is a couple of helpful links that some one gave me that I will pass on to you guys also… thanks…it is nice to cruse again.



http://www.mindspring.com/~houlihan/merc/cruise.htm

http://cathey.dogear.com/SDLcruise.html

http://cathey.dogear.com/cwcruise.html

http://www.mbca.org/pages/tech/MBCA_Troubleshooting_cruise_cont.htm


There are others but these are good ones…
 

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'87 560SEL, '97 S420, 92' BMW 535i(EURO)
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56 Posts
I have had the same problem. I took me me a while to find out whats wrong....
1. Check Actuator - carbon pads on reference resistor and Big Gear which actuate it(usually only one teeth is brocken) - e-mail me if you want to know how to fix if it without purchasing new actuator,
2. Cruise control amplifier - There are two type of amplifies I sow - one with a one big microcontroller inside and bunch of small parts another just binch of small parts. To fix amplifier without microcontroller I think way chipper as this microcontroller is about 150USD. You need oscilloscope to check if internal ocsillator still clocking... If no clocking on pin 44 probably cheeper to buy another amplifier. If internal occlilator clocking ok - it is probably cluch control transistor(0.75USD) or Comparator(0.85USD) both avalable from RadioSHak... If you intersted I can tell you more what and how. As my Cruise control fix from 700USD(quoted from local mechanic) went to 0.85USD and no labor cost!
 
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