I have a non working cc in my -86 D250. Recently it has developed a noise, best described as a pulsating grinding sound, that seems to be coming from the front left side of the truck. It's speed related in the aspect that it's in relation with the speedo indication. Also, the speedo needle is fluctuating in sync with the grind pulse.

The only thing I can think of that may be the cause of this is the cruise control unit mounted on the left fender well in the engine compartment. The proper way to solve this is of course to replace the two speedo wires with one non-cc wire but for now I need to simply make it work.

Is the cc unit something that can be taken apart and cleaned/greased?

 

It may just be your speedo cable which as you note is a two parter. I just bought a cut to fit kit from O-Reillys and it fixed my 86 non op speedo and the cc (I replaced both cables). My main problem was the lack of a speedo and I never tried the cc bfore I replaced the cables but both work now. I do remember hearing a grinding sound though as the cables were dry and the ends stripped.

Just noticed your from Sweden so the OReillys reference may not be recognized, basically, a universal speedo cable kit where you cut to length and crimp the square cable end on should work.