Is the Cruise at all controlled by the Vacuum system on these cars?

My Cruise went out so I went ahead and pulled the control (i think it's called a cruise amp, the thing with all the linkage attached to it to the right of the valve cover) off a car at a junk yard for $10. I'm in the process of trying to get all the vacuum components working again and recently rebuilt the vacuum pump as well. Now i'm working on tracking down the door vacuum leakes.

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1985 Mercedes 300DT

No that is NOT the amp. Amp is located under the dash on the drivers side. It's a metal box about the size of a VCR tape.

looks something like this:



this is most likely your problem

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

Your vehicle has an electric actuator under the hood. That's the part that you're seeking from the junkyard.

However, it's usually the cruise amp, as shown in the photo above, that gives the most problems.

doesn't look like something that vacuum lines would go into... thanks for the clairification...

I should explain my problem a little more to get a correct diagnosis...

Cruise would hold and then all of a sudden stop, like when i hit the break..with a little finess it would start working again...then sometimes it would just start speeding up like it was floored...then would stop again... cruise is nice and i'd love to get this thing fixed...thanks for the input..

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1985 Mercedes 300DT

........amplifier problems........

You can try resoldering all the connections on the circuit board yourself with a fine tipped soldering gun (just don't bridge any connections). It works for some people but not for others. There is a site that will rebuild the cruise amp for you- kind of pricey though. Be forewarned that that site may not take an amp that has been butchered by a bad solderer.

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Andrew

1989 Volvo 745- 202K

If you take the circuit board out of the can...you may see some loose solder joints that could be resoldered for an easy fix if that is the problem....A lot of these under dash enclosed circuits vibrate loose after 20 or so years.....especially the heavier components on the boards.....might be worth a shot to save some $$$....you can see the cracks on the solder side pads by pushing the components around gently....

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

i'm glad i posted this before changing the thing under the hood...i'll take a look at the cruise amp...under the dash on the drivers side? I should be able to find it..thanks for all the input...this site really is the best place for DIY questions...

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1985 Mercedes 300DT

Check this out http://www.gdl-online.com/testproc.html good luck.


edited: thanks Craig

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83 SD

84 CD

that link isnt working.

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1980 300D

Try this:

http://www.gdl-online.com/testproc.html