89 suburban cruise control problem

[old man jimmy]

anyone found the answer to this problem with cruise? Works fine cold for a few miles, then kicks off. Colder it is longer it stays on. And when it's starting to warm up, will work uphill but when it lets up downhill, it won't kick in again. Sometimes you can push the pedal down & will catch. Have replaced cruise control modual, and turn signal lever(with the switches) still the same thing. Must have a speed sensor of sorts somewhere, but don't know where or what it even looks like. Speedo cable goes from speedo to trans one piece.

[BLE 'BURBAN]

Have you checked your vacuum lins for possible leaks?
Since your Speedo is the old school cable driven style, you may want to check the back of the speedo itself and see if there is what looks like a couple of wires held in place with a retaining screw. If it's there then that is the "HALL EFFECT" pick up for the cruise control.

[gchemist]

http://elcaminocentral.com/article107.html

I ditched the factory setup for a www.rostra.com. Worth every penny.

[old man jimmy]

Ok Burban, at the risk of sounding stupid. What is the "Hall Effect?" Only guessing, sounds like the dilly whap to measure the speed. And have replaces all vacuum lines. Sill no change. Their's a vacuum diapham thingy on the firewall with rod to TB. But haven't replaced it. Can't find one. And checked the rostra.com site. They don't go back to 89. Will check for the wires behind speedo. Thanks guys.