Cruise Control Fix

[rmmagow]

Anyone know of a site describing the repair procedure for the electronic cruise control amp in an 83 300CD? It's the one with 14 pins I think. I have a spare broken one and am thinking to attempt a fix since I heard it's sort of a simple soldering job.
Thanks.

[Q]

I posted my experience in this forum category. Should be pretty easy to find.

[jbaj007]

Hopefully of help: http://www.mbca.org/pages/tech/MBCA_Troubleshooting_cruise_cont.htm

[David Speed]

My Cruise Control works........but the cruising speed slowly drops ~ 3mph every 5mins..............I'm very happy to have a CC that still works after 25yrs, but it would be even nicer if I didn't have to give it a nudge up every 5 minutes or so

Any ideas on which area to look....or is it a comon 'feature' of the CC of this vintage ?

[MTI]

The VDO cruise control, and there are several types that MB used, does have some "weak points" as most of vintage owners know. From around 1976 to 1980, the system was vaccum activated with a 10 pin amp, while from 1981 to 1993 it was electronic with a 14 pin amp. Since 1993, the cruise control has been integrated with the "engine management" computer and by removing the additional amplifier, made it more reliable.

Here's a link to a nice comparison article:

http://gdl-online.com/differences.html

[David Speed]

MTI.....thanks for the link to the VDO CC info

Quote: 'All of the 10-pin amplifiers store the "set speed" as an analog voltage at the junction of a capacitor and the gate of a dual-gate field effect transistor (FET)'

Seems a leaky capacitor at that gate would be the likely suspect........probably an easy fix to try if I could identify the FET & capacitor.........replacing all the capacitors could be an option........may consider it if my cruising speed drop rate increases

Anyone have info on the board layout or circuit diagram?

[luvmysd]

I just wanted to say thanks to the original poster because this post inspired me to go resolder my cruse amp and now it works again woohoo!

David