I've searched through 17 pages and didn't find any good ideas on this one. The cruise control in my 84 300sd works great until it gets a little chilly outside. I saw this problem tonight and it was 41 degrees outside. It doesn't engage at all until the engine gets warm. Once my temp guage gets close to 80 degrees it starts to try to work. When I try to set it I can feel it engage but it won't hold. But it will accelerate until I let go of the switch. After about fifteen minutes of driving it works perfectly again. Anybody seen similar problem??

__________________
U. S. Air Force Air Traffic Controller
"U gotta keep 'em separated!!"

Sounds like an electrical problem....when the contacts warm up and expand they make connection and work............you need to look at everything closely.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

boneheaddoctor,
That sounds like a good theory. Where do you think a good starting point would be? I had to resolder the contacts in the actuator on my 380se. After I did it the cruise worked fine for a couple of days but then when I tried to set a speed it would accelerate uncontrolably all the way to 90+ mph !! I'm kinda scared to mess with the actuator in this one. Are there any contacts in the unit under the hood?? I've never opened up one of those. Since it's related to temperature, it seems to me that the problem would be near the engine. What do you guys think?? I'm slowly learning how this car works and so far I'm loving it!! Thanks for all the help.

__________________
U. S. Air Force Air Traffic Controller
"U gotta keep 'em separated!!"

I would try the connectors first....those are most suseptible to corrosion...before you resolder the computer keep in mind doing that ruins its core value..if you even thought of going that route......the Actuator? never had one apart so your guess is as good as mine. Problem is at this age it theoreticly could be almost anything.

I got a used recently remanufactured cruise computer on Ebay for mine for way cheap.

I will say the odds are pretty high the computer under the dash is going bye-bye.....thats the most common failure I understand.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

mine is doing the same thing, but it is 20+ years old. I find that if I set it while accelerating it holds better.
Some months will work flawlessly, other times it does not. Not a real issue at present but did want you to know that it is a common problem as the electronics age.
It seems I am becoming more tolerant of these types of issues
Perhaps because I myself am aging and some of my systems malfunction from day to day.
I try to take it all in stride

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Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
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19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace

Here are some trouble shooting tests you can do:

Cruise troubleshooting

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

Thanks for the feedback and the link, looks like lots of good info on their site. I never even thought about core value on the actuator. I think I'll leave it alone just in case. I'll go through and check all connections as suggested. However, on the way to work today I discovered a new, klunking noise coming from somewhere in the rear of the car, mostly on left turns. So for now I have to track this down. I may be starting a new thread on this tomorrow. Right now it's sleep time. Thanks again.

__________________
U. S. Air Force Air Traffic Controller
"U gotta keep 'em separated!!"

My 83' SD did the same thing until I got a friend to solder anything that looked bad in the cruise computer. It has worked for over a year now.

__________________
1983 300SD 343K everyday car
1983 300SD 285K from junk yard-tooks parts from deer car- runs great. Brothers car.
1984 300SD parts car-Hit deer
1979 300D 175K non-turbo "Doctor"
1979 300d parts car