Ernie,

Very interesting.... that the brake light ground would act as a switch makes sense to me. What did not is that the current draw of my brake lights should go through my CCU, thanks.

Does anyone doubt what Peter says in this article?

Rgds, Ed

__________________
Ed "Don't Benz's just feel better..."

Current wives...
2000 ML430 Skyview "The Mel"
2000 CLK430 Cab "The Cab"
85 300D Turbo "The Diesel"

Past wives...
92 300E
85 190E

"One should as a rule respect public opinion in so far as is necessary to
avoid starvation and to keep out of prison, but anything that goes beyond
this is voluntary submission to an unnecessary tyranny, and is likely to
interfere with happiness in all kinds of ways."
Bertrand Russell

ML Dude,

I agree with Peter's article. I even had a third brake light hooked up, and the cruise control still worked. It really doesn't matter which brand of light bulb you use. Some people will swear that the brand of bulb fixed their cruise control problem.

Greetings All,

While the original bulbs may be Osram which is also Philips in the States, too many people replace the bulbs with the wrong contact point that ends up using the power side but no ground. Yeah, I agree that most proper sized and configured bulbs will work, but I have pulled several rear bulbs out of my own vehicles after obtaining them that the contact points were not was called for but still worked in the bayonet mount. That's why they mention to stay with OEM bulbs. They're cheaper too.

Charles

__________________
"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan

Okay, what types of bulbs are used? I assume they're not 1157's

Personally, I'm a big fan of the extended-life Sylvania bulbs (use 'em everywhere except headlights; there I use the Xtra-Vision bulbs)...just wondering, any thoughts there?

__________________
2001 VW Jetta TDI, 5 speed, daily driver
1991 Ford F-350, work in progress
1984 Ford F-250 4x4, 6.9l turbo diesel, 5 speed manual
Previous oilburners: 1980 IH Scout, 1984 E-350, 1985 M-B 300D, 1979 M-B 300SD, 1983 M-B 300D
Spark-free since 1999

Is this amp in the same place as described on a 1980 300SD?

Greetings,

The '80 is a 123 chassis while the '84 is the SD 126 chassis but both under the dash seem to keep the same general location for their components.

Charles

__________________
"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan

I just did my 82 300d, and the information you are getting is correct. Two things I wish I would have know before I started is that the nut for the 10 mm bolt is made as a part of the bracket, thus there is no need to hold it, and when reinstalling there is a protusion on the bracker that goes into a hold to assure correct position of the amp. I recommend removing the drivers seat so you can be comfortable while you are doing it. I sat on the ground beside the car and still have the bruses.

82 300d 194k
75 240d sold

The pain is for real -- I did this last night on my 300TD. I, too, have (had) an all-electronic system which became increasingly difficult to engage, then stopped altogether.
Accessing the 10mm bolt requires big guys like me to be contortionists, and I may well wind up pulling the front seat to reinstall...but the bolt is best accessed by using a 3" ratchet extension and I found once I broke the bolt loose a ratchet wheel worked best to remove it. Not a lot of room to work!
What I'd like to know is whether there's any test to see whether the darn thing has cold solder joint(s) without sending it to CDE or open, resolder and pray? My M-B disc simply instructs to swap the unit out and see if that fixes the problem, which strikes me as inelegant.
My unit (#001 545 7932) has 14 pins which BEG to be put to a meter -- does anyone know which pins should yield what readings??? Thanks!

I soldered mine several times only to have it fail.
You need a big lighted magnifying glass and steady hand, and heat sinks.
I got a rebuilt amp and speedometer.
They have worked perfectly.

__________________
82 300d 194
75 240d sold
Gulfstar 41 4-107 Perkins Westerbeke 4.4 Gen
Puegot Bicycle Legs
AYP Lawn Tractor Briggs 12.5

I had a problem which I posted in this thread
I tightened up the cruise actuator cable to remove all slack and it works a charm now.
I hope this helps.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

Thanks for the input! I opened my amp to scope out the soldering job and my blood ran colder than the prospective failed joints! Many, many closely-spaced solder points and worst of all the board (and the amp) LOOKED wonderful. In spite of the reassuring words on the "soldering thread", based on my personal history with this craft I'm skeptical that I could satisfy the Hyppocritic Oath of, "First, do no harm!".

But the larger problem continues to be that I have no confidence that even were I successful, that resoldering the amp would fix the problem. All it is winds up to be a less-cash, more time-consumptive swap-and-drop approach. God help me, but I'd really like to know what my problem is before I slide into serial putzing around. It's just a car, after all, not my life!

I've contacted various independent shops in metro Seattle for input and the best advice seems to be to take it in to the dealer which apparently has the special diagnostic rig to provide a definitive answer -- does anyone have a better suggestion?

My cruise doesn't work at all. HOw do I tell if it is this amp, or the other component (which I forget what it's called)? I have a multimeter, can I test with this? Where and how and what should the readings be? Also, is the 81SD vaccum or electronic?

Unless one has been put in in the last 3 years or so, 9 chances out of 10 it is the amp.

__________________
82 300d 194
75 240d sold
Gulfstar 41 4-107 Perkins Westerbeke 4.4 Gen
Puegot Bicycle Legs
AYP Lawn Tractor Briggs 12.5

http://www.fix.net/~gdl/begin.html

On that site is everything one needs to know to be sure if it's the amp, the servo, or the control stalk. Read.


That being said, I'm looking for a good reason that a rebuilt amp is going to last any longer than the originals did. You could say that replacing the amp every 2-5 years isnt so bad, and in a way it's not, but I intend to explore other alternatives. Aftermarket cruise controls mostly. There is at least one other member on here that said he was going to try an aftermarket unit. The Mercedes unit is great when it works, but it just seems awlfully fragile.

I also have a young electrical engenering student whom I'm trying to talk into takeing these amps on as a summer project, to fix and/or imporve on them some.

__________________
One more Radar Lover gone...
1982 VW Caddy diesel 406K 1.9L AAZ
1994 E320 195K

There are a lot of references to GDL in this thread, and on this topic in this forum. So many that my first attempt to fix my cruise control was with GDL. You can read what happened here. As it stands right now, my cruise is still inoperative, and I did everything that Peter at GDL instructed me to do, except send it back yet again at my own expense. I gave them every benefit of the doubt. I think I'll try one from the link sainttammany posted and see how that goes. GDL was a big waste of my money...

__________________
1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick