Cruise Control Issues 1987 SDL
Thread Starter
Senior Member
Joined: Oct 2008
Posts: 335
Likes: 0
From: MA
1987 SDL; 2001 Chevy 2500HD CC, 8.1L, Allison special order; 1970 GTO LS2, 4L60E, under construction
Cruise Control Issues 1987 SDL
Anyone know how or where I can begin my diagnosis on a cruise control that doesn't work? I need it to be functional by the time I drive it to Florida at the end of next month.
Junior Member
Joined: Jul 2008
Posts: 16
Likes: 0
From: Melbourne, FL
2010 GL550, 2008 CLK55
i remember the first time i was told that the cruise control electrobics go bad over time - it was on a 1982 300SD. i thought it could not be true, how could a motherboard fail? but these do - believe me. the under hood components RARELY (if ever) fail, but the aluminum-boxed cruise contol brain mounted under the dash goes bad. the soldered joints and connections on the board fail over time of use (meaning the cruise brain in an older car that has used cruise control rarely will still be in better shape than a newer model that has had it's cruise control used often). it easy enough to replace - remove the sound insulator panel from above the brake pedal, unplug the multi-pin connector from the cruise box, remove the clip that holds the box in place, wiggle the box out of the mounting tab, and remove. i removed the box in my 1989 560SEL and replaced it with a couple junkyard duds until i found a good one - out of a 1991 E-Class - and it has operated since.
Thread Starter
Senior Member
Joined: Oct 2008
Posts: 335
Likes: 0
From: MA
1987 SDL; 2001 Chevy 2500HD CC, 8.1L, Allison special order; 1970 GTO LS2, 4L60E, under construction
I weas reading on another forum that there are actually three different boxes for different models. Sounds like you got lucky finding one.
So far, the cheapest one I've found is $195 rebuilt. Over $300 for a new one.
I also read an article on how to re-solder a unit, but I haven't done that before and don't have the proper equipment. Plus, from what I understand, if its done and then doesn't work, you can't exchange it for a rebuilt one.
So far, the cheapest one I've found is $195 rebuilt. Over $300 for a new one.
I also read an article on how to re-solder a unit, but I haven't done that before and don't have the proper equipment. Plus, from what I understand, if its done and then doesn't work, you can't exchange it for a rebuilt one.
Junior Member
Joined: Jul 2008
Posts: 16
Likes: 0
From: Melbourne, FL
2010 GL550, 2008 CLK55
i think you and i read the same online ad. i thought about re-soldering mine as well, but i pryed open the box and it looks ridiculous inside. there is probably 150 joints to solder - none of which looked like they are bad by the way. each one the size of a pin's head. and i, too, read that the same compoany who will BUY non-operating units from me will not purchase one that has had an attempted repair performed on it. the junkyards here in florida are littered with 1980's and '90's mercedes models, so finding a replacement wasn't difficult, it just too 3 tries for me to find a good one. the original in my car was just plain dead, the first replacement worked - but it would sometimes only hold the set speed for a short distance, the second one was just bad, and then the third, was out of a low-mileage e-class and it operated perfect - it's what's in there now. i did read that there are a few different boxes, but they use different looking connectors, so it's not like you could install the worog one - the pins on the connector would not line up.
