I have never heard of a schematic around for the cruise control or anyone mention they have one. I believe I read on a euro site the shotgun approach to recondition them. Never could find the site again when searching though. Spent quite a bit of time at it. Not a bad deal really as all the components they mentioned are pretty cheap.

Anyways from what I remember all the electroylitics and several transistors should be changed out with more reliable current types. From what I could tell that gets about ninety percent of the problems out and increasers reliability a lot. Why I wanted the site again is I believed the early ICs could stay as they where not mentioned as being a problem. There may be something to this as the true rebuilders of them out there have claimed they are much more reliable after the reconditioning by them.

Rather than cold joints although a possibility I wondered if the transient heat from resoldering connections reactivates a given component. Yes there is a market for a decent replacement in my opinion.

Now if someone told me the european giant phillips made them for vdo or mercedes in the 1980s cold solder joints are a distinct probability. For it's size and experience that company was a disaster in my opinion.