Originally Posted by big dog 2

I may be way off on this but it is my understanding a lot of these cruise control amplifiers are "universal" and my fit other makes and models. The coding attachment from Mercedes is the "brains" that will make it operate for our specific model.

In my case, it appears my original amplifier was the issue. The replacement amplifier was OK but the coding attachment was the issue. Switching the attachment appears to have solved my problem, at least temporarily. You never know with these old parts!

I believe it was the GDL website that also mentioned coding issues account for many cruise control problems along with the amplifier.