What else is there to the cruise control
 

My cruise doesnt work. So i removed the amplifier, cleaned the pc and resoldered the entire thing. nothing was burned or shorted, and there seemed to be no cold solder or cracked points. but i did it just in case. well cruise is still not working. what else is there that can be a diy job? no blown fuses by the way. is there any way to check the cruise control actuator? if so, what methods. the fsm has nothing on it that i see. any ideas? thanx

If no one beats me to it, at home I have bookmarked one heck of a cruise control troubleshooting article. The link is burried somewhere here in the archives but I have it bookmarked at home but I'm at school now.

Where is the cruise amp for a 1980 240D? It has the vac cannister type of cruise unit.

i dont know about a 240.
EDIT: i see in the fsm cd i have that the 240 is the same as the 300. it has an amplifier by the break pedal mount. as well as the actuator on the inside fender. the diagrams for these two look identical.

now that i have found this, does anyone know the number and location of the brake sensor? its raining right now and i havent been able to locate it under the dash and now half my body is soaked. :confused:

Interesting. Might help.
http://www.peachparts.com/shopforum/diesel-discussion/178676-brake-light-really-problem-cruise-control.html

yes ive been watching that. but unless i have a broken ground from brakes back to the cca....this would not be my problem i would think. because my brake lights work fine. although i do have the 1157 bulbs in them. but when i bought the car, no cruise, and it had bosch bulbs in it. one burned out so i replaced them both with 1157.

Nevermind
 

cruise is working amazingly. i obviously did not get the connector back on completely as it was hanging down when i took a second look. pushed it on nice and tight and its working great.

the sun is out the rain has stopped isnt life grand and retx has cruise

Yahooee. Awsome. Sometimes it's the silly things...

yeah i know, thats a great thing. one thing at a time, is all i can hope for. and here i was thinking it was going to be something more complicated. eh, im not perfect.

Anybody have a pic of the cruise control amp. Is it a big sardine can looking thing?
The 240's have some type of sardine can looking thing mounted to the underside of the driver kick panel. What is that for?

The amp in my 300TD is a metal box that is near the outside wall on driver's side under the kick panel.
Here's what mine looks like.
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1L00T87R020I0O6YUF&year=1982&make=MB&model=300-TDT-001&category=All&part=Cruise+Control+Amplifier

Check your brake lights



in the 300d (w124's atleast) the CC is wired through the same circut as the brake lights.

jimmy, i can take a pic of mine easily if you still need it. its only one bolt holding it in, so i can take it back out no problem. in my 300, it IS a big sardine can looking thing. with the black 8(?) pin block connector at one end of it. the other 4(?) pin connector is connected in line on mine and not part of the can like i believe some others are.
http://www.peachparts.com/shopforum/diesel-discussion/90684-yes-we-have-cruise.html?highlight=cruise+control+amp
post 15 has a pic of one. mine has black plastic rather than the beige.

That W126 amp seems to have more pins, but I get the idea. Guess I will go see what my 300D has. With not dash or seats it is easy to get around in....:o

That's the cruise amp.

Can someone post what the control lever is supposed to feel like in the different directions?
On mine, I can feel the slight "clicks" in the up and down (accel/set and decel/set) directions, but in the front to back (resume? and off) directions it feels really squishy, and there's no definite click or anything to tell me that the function is being initiated. I've never tested it because I assumed it didn't work. Do you just push the lever up or down? I'll try it today...and if it doesn't work and the lever isn't messed up, I guess I'll pull the amp and see what it looks like on the inside.
Can someone post a link to the tutorial mentioned earlier in this thread. Well, I can probably search and find it..I won't be a slacker :)
thanks,
-geoff

Careful. If you open it and decide you want it rebuilt, you might be out of luck. The main amp rebuilder wont work with one that's already been opened.

I swapped the cruise amp from the '77 300D into the Squash. Before the swap, nothing would happen via the cruise lever. After swapping, the cruise lever will accelerate the car, and it will hold speed below about 45mph, but only within about 5mph.
At freeway speed it doesn't really work.
It looks like I need to tighten up the cable slack a little bit, which might help with consistency of speed. Also, maybe the extra slack might be keeping it from working at highway speed, as accelerator has linkage moved farther, and maybe too much cable slack to do anything?????
I at least know that the original cruise amp is no good, so may open that one up to see what is going on in there.
I also have an amp out there in Scar. May try that one too....

Oh, so it isn't recommended to try and fix the amp yourself? If that's the case, I'll leave it alone.

Can anyone help me out with the squishy feel in the control lever? Is that normal for the resume and off directions?
Thanks,
-Geoff

Yes, that is how mine feel.

Send it here: http://www.gdl-online.com/begin1.html

from what i have read, its just cold or weak solder points on the amp's pcb. its a pretty simple board, with about 30 or so resistors, a ic or two and a rectifier or two as well. just be careful with pull through when youre reheating the points and you should be fine. use a lower watt iron with a good tip. watch for bridging. wash the pcb with cleaner or alcohol and you should be ok. i say this from building circuits myself so....to me its second nature.
im thinking my only other problem now is something to do with the cable to the actuator or my speed sensor...when i set the cruise...it accelerates upt to 5 mph before setting. so if i want it at 65...i have to actually set it at 60.

Holy cow, $215 to exchange my broken amp for a good one...that's quite a charge for basically the labor..am I missing something?

Well, I have heard they're ridiculously expensive parts. I'll have to see how mmuch highway driving I'lll really be doing to see if its worth it.
Thanks for the link.
-Geoff

I officially have cruise control in the Squash!! It only took 3 different cruise amps to find one that worked. And it was the one out of Scar!
So, the original didn't work at all, the second one only worked below about 45mph, and didn't hold speed very well, and the third works perfectly. I had no idea these old vacuum cruise controls would work very well, but my '79 Chevy PU has a vac unit, and it has worked perfectly for 28 years now..........

hey jimmy, since you have a few to spare...go ahead and take one apart and try to resolder it all. it worked for me.

Yep. First I am going to take apart the one that didn't work at all and try re-soldering that one.
I haven't permanently mounted the working one yet, so I can swap them easily. I'm still just shocked at how well this old cruise system worked.

Geez Louise there is a lot of stuff in there!! :eek:
I couldn't see anything obvious inside of the one I opened up, which was the one that didn't work at all. When I opened up the can and pulled out the circuit board, it had that unmistakable smell you usually get when something fries, but all looked well. I guess I will try and re-melt all of the solder joints [of which there are plenty!]
Ah, we'll see.........

May attach pics later. This 65kb image restriction is just stupid! 100kb would be a much better limit, but I digress......