I have a 1993 MB 300E 4matic and the cruise control is not working properly. When I activate it, it does come on but is erratic and does not hold its speed it jumps and stops?? What is the problem? Can some one explain why it is doing this and how I can fix it ? Do I need a new cruise control switch, ECU relay, module or is there a vacuum hose problem or amplifier? Please help me since I am new to this car and it does not work as it should. I love this car and I just replaced the transmission and want to restore it as best I can.
Thanks, Leo

Is it possible to reply to me at my email leodrco@rogers.com thanks, Leo.

probably the amp like mine, its a ***** to get to next to steering column under dash

My 1994 E320 Sedan has the same problem. It's good up to about 40 mph, then goes awry. I've read about that box under that dash, but havn't bothered with it. The pedal on the E320 is pretty comfortable to hold in place without having to hold your foot UP like you do in most other rails. I've also wondered if there's a lubrication requirement on the cruise control assembly?

I would suggest the amplifier may have poor solder connections. I have fixed one amplifer by re-melting the connections on the printed circuit board. Took some time and was a risk of having it not work at all. If the repair failed I was just going to purchase a rebuilt unit. However, it works well now.
Best.
(my repair technique is outlined on one of my previuos posts)

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86 300e 460,000 k