95 e300d cruise control intermittant between 50 and 60 mph

[DickJ]

My 1995 e300d cruise control gives a "bucking" or an intermittant on/off/on while trying to maintain the speed between 50 to 60 mph. At any other speed other than between 50 to 60, the cruise control works normally. The Mercedes dealer indicated it was a bad cruise control amplifier. Since this was easy to replace, I put a new one in and the same problem occurs. I did not buy a new "coder" which plugs into the amplifier. I used the old one. Anyone have any ideas on what to check next or replace? Perhaps there is a speed sensor loose or defective but I do not know where to look. Thanks, Dick

[DickJ]

I checked the code plug for the amplifier per the MB manual and it checks out ok with the correct resistance levels. Also, checked the connections on the code plug and the amplifier plug. Good contacts there. The hints and troubleshooting guide on the cruise control section indicated it might be the "Hall Effect" Speedometer Transmitter mounted on the back of the instrument cluster. I put a new Speedometer Transmitter in without luck on fixing the problem. Also tried a new amplifier. Checked the round sleve connections on the plugs and reshaped all of them. Shaking problem still persists in the speed range of 50 to 60 only. Checked for corrosion on the X26 plug in the relay box and reshaped connections there too. I did the same on the plugs behind the instrument panel cluster on the right side. Then I called the big guns (GDL) who repair all these components. They are thinking it is definitely the acutator. Now I am tearing into the actuator on the potentiometer board to check for a wear spot. Getting a real education on cruise control here and what to test and not to test. This should be interesting to see how tough it is to get the actuator out and opened up. Pretty sure I am putting a new one in at this point. Here's a link that you may want to look at if you experience a simlar problem. http://www.gdl-online.com/act_boards.html Has good pics of what problem is. More on this when I get the energy and mind set to open the hood again. Electrical parts used so far will be put up on eBay soon as they did not solve the problem....amplifier and speedometer transmitter.....Dick

[lorenztl]

Originally Posted by DickJ

Shaking problem still persists in the speed range of 50 to 60 only. More on this when I get the energy and mind set to open the hood again. Electrical parts used so far will be put up on eBay soon as they did not solve the problem....amplifier and speedometer transmitter.....Dick

Dick, Have you solved your cruise shaking? My 95 E300D has symptons similar to yours however in light throttle or downhill situations and recently has begun to disengage altogether soon after setting speed.
Thanks, Tom

[WINGAS]

An education indeed! A slight consolation that you've alreaded added to the knowlwdge base here. thnx.