How many have re-soldered their cruise control?
 

I finally got a spare 2 hours to try the often cited procedure of re-melting all the solder joints on the cruise control brain box yesterday. It had all the symptoms of this being the problem - erratic/sporadic kicking in of the function, going off as soon as you let go of the lever, bucking and hesitating when it did work, etc.
I'm delighted to report that it now works perfectly! The price of these rebuilt or new is absolutely out of this world, IMO, and this is such an EASY FIX!
A couple of tidbits on the procedure:
- On my 380SE, the bolt that holds the control box bracket to the brake pedal assembly is easiest to take out with a 2" extension and ratchet with a 10mm socket to loosten, then use a palm wrench to turn it out of the bracket.
- Goof Off works well to remove the gummage from the little piece of foam strip stuck on the circuit board, as it doesn't eat the printed circuit board coating.
- Use a magnifier light to work under, and frequently dip the iron tip in flux paste then wipe to keep it clean.
I was wondering how many others had done this job too, and the success rate?

Good threads for reference:
http://www.peachparts.com/shopforum/diesel-discussion/90684-yes-we-have-cruise-3.html
http://www.peachparts.com/shopforum/diesel-discussion/123036-cruise-control-repair-articles.html?highlight=cruise+control+repair

Finally found: Article on adapting the stock MB cruise control stalk to an aftermarket kit. Here's the link to the thread, which has a handrawn wiring diagram, about 3/4 way down! http://www.benzworld.org/forums/forums/thread-view.asp?tid=1228742 This is the kit that he is connecting to: http://store.summitracing.com/default.asp?target=egnsearch.asp&N=400615+314455&autoview=sku

I resoldered mine and got it to work half the time. It looks like I need to remove it and try again.

I tried, and failed... I need a new one :(

Shouldnt have toughed a $200 part with a $5 wallmart sodering iron


~Nate

I had someone from the forum resolder mine. He is a professor who teaches electronics, and he tested out all the components, except for the microchip. I believe he said the chip is programmable...and that the only way to test it is to know exactly what the programming is.

It turned out that, yes, the joints needed resoldering...but also the electrolytic capacitors were bad. He replaced them, as well as the other caps...and sent it back to me.

When I sent it...it did not work at all...nothing...zippo. When I got it back....the cc now works sporadically. This particular car is from the east coast. It has lots of rust underneath...and there is corrosion around the engine compartment, so I am inclined to believe that other things are mucking with the cc. So many things can screw with it...speed sensors...tail lights..who knows...this car was not well cared for.

My other 1990 300TE is a California car...in excellent condition...no rust...just beautiful...and the cc has always worked perfect...never a hiccup.

You might want to consider replacing the caps since you have the thing out. He did say that one in particular was a strange value.

Mine likes to accelerate randomly. Set at 75 will eventually cause it to floor it and go to 85-90 by the time I kick it off! I soldered mine and it is a bit better but I think I have a bad Cap in there somewhere or other component.

Bad caps....hmmm Never thought of that one :bulb: . I tried this twice on my 82 380sel To no avail. Worked great on the acc and Idle speed control. I also went as far to resolder both plug ends: accuator and amp. Anyone know which capacitors are/go bad? Are they electrlytic or the germaniun type and what farad rating are they????

For some reason FLUX seems to make it a lot easier to resolder.
I file the point of cheapo irons to a thin point dip into flux and touch old solder.

Caps are electrlytic,

Generally, they change in capacitance and get more resistive with age. 20 years with hot enviroment ... Yes, I have replaced caps. I'm not sure how mr Prof tested them. To test, he would have to remove a lead.. probably just threw parts at it for good measure (a couple pennies out of the lab).

My experience with caps(not dead or toasted black marshmellows), was they made improved the range of speed holding. It did nothing for flaky operation, just when it worked- it worked better.

Michael

I was going to try to resolder mine awhile back. Unfortunately, it had a really thick coat of clear paint or something on the circuit board that I couldn't get off.

I bought a used one and it works great.

You can solder right through that coating on the printed circuit side, no need to remove it...and while I'm here, I added links to my original post to another board/thread on how to adapt the stock column stalk to an aftermarket cruise kit, made by Rostra (and which looks like a VDO Tempostat). This might be good stuff for anyone who has to spend more than $200.00 on their existing setup to get it operational.

Successfully resoldered cc module, idle speed module and fuel pump relay. Of course, I have taken a week long soldering class. :)