Cruise Control Works after Given up for Dead
 

When my cruise control amp went out on my 92 300D, I did a bunch of research and had my amp rebuilt by GDL (interesting outfit, interesting guy). When I reinstalled the amp it burned out again after a couple of works, so it appeared as if I also had a bad actuator which was drawing too much current and thus frying the amp. So at that point I just gave up and decided to live without cruise (I'm sure needing to spring for two weddings within 12 months had something to do with this!)

Then I bought my 91 300D in April of last year. When I test drove it and tried the cruise, I felt it surge for a few seconds then immediately die. Tried and tried again....nothing. So I assumed I had another burned out amp.

Every once in a while, just out of boredom and curiosity, I would try the cruise. Absolutley no response.

Then TODAY, after owning this thing for a year, I tried the cruise and it WORKED PERFECTLY!

So who knows....bad contact somewhere?

Perhaps the self-healing car is part of the magic of Benz ownership....

Mine did this too, sort of.

When I bought the car the CC did not work. On my long drive home I tried it and the engine wet to full throttle. Hit the brake pedal and it turned off as it should. Tried it again and the same thing! It never has never regained consciousness in any way again in the one year I have owned it.

I've always figured it was the control module and I do plan on fixing it eventually.

I just ordered and received a rebuilt amp and am planning on switching it out this weekend. Hopefully it will work for more than just a few times before it burns out again. Those rebuilt amps are expensive!

What I learned is that, in many cases, the cause of a bad amp is a bad actuator. I didn't troubleshoot the whole system...simply rolled the dice assuming that an amp rebuild would do the trick.

Do you know WHY your amp was bad? If not, then it is a gamble.

Happened to my windows on the right side!

I had my mechanic check it out and they said it was a bad amplifier. Of course there's always the possibility that it's the actuator. I guess the good thing about buying a rebuilt (Programma) part is that it's under warranty. I haven't even looked at what new actuators cost.

I'll just have to keep my fingers crossed. ;)

Can't you disassemble and clean the actuator internals?

Yes. GDL will do an actuator tune-up for $95.

its cheaper to replace with aftermarket cruise unit. (If your not a true purist) LOL. Here's the link: http://www.peachparts.com/shopforum/showthread.php?t=219993&highlight=ccs-100

Looks like price for Audiovox unit is about $250 these days. Sounds like a good alternative if both amp and actuator are bad. But, if it's only the amp, a rebuilt amp can be had for $215 or so.

There's another aftermarket cruise unit....made by Rostra. Have wondered about it as well.

In general any aftermarket system should* work.

* your mileage may vary. But the all the inputs for a cruise control to work are available at the cruise amp connector, even VSS. Looks like Mercedes uses 8000 PPM.

Yeah, it sounds like this is a common thing. It seems to work fine on mine, as long as the inside temperature is not too cool. But, If it gets too hot inside, the turn signal relay stops working. :bigcry:Go figure.