The cruise control on my '81 K30 doesn't work, nor does the cruise in my '85K5 anymore. I'd like to get the cruise working again in my K30 CC as I use it every day. My first question... Does the cruise use the speedometer at all? The speedometer does NOT work in neither of the two trucks in question. This makes me highly suspicious of why the cruise doesn't work, but I thought I'd get some input even before fixing the speedo to learn something new today. How much electronics are involved with these cruise systems? Are they generally a pain to diagnose or are they simple and easy to fix, generally? Are the two setups between my '81 an '85 exactly the same and interchangeable? I'm figuring yes, but you never know. If for some reason my inoperative speedo ISN'T the cause of no worky from the cruise....what would be your best bet on how to start a diagnosis plan and/or what do you think the culprit could be?