My question pertains to the cruise control. The cruise does set, and operate but it will not hold a steady speed. It fluctuates 5-8 mph even on level road. Help my OCD doesn't allow this. Any suggestions would be greatly appreciated. So far Ive cleaned the contacts in the steering wheel, and changed the servo. Still pulsating. Any ideas?????

 

The cable that holds the throttle open and adjusts it uses Vacuum from engine.

Vacuum part seen in this diagram: http://www.therangerstation.com/tech...ntrol_1of2.JPG

Check the vacuum line from servo to intake, and the vacuum line to the brake pedal.

Next is the VSS(vehicle speed sensor), I assume the speedometer is accurate, no jumping up or down of the needle.
In 1993 the speedometer used a cable drive but the Cruise and computer used the VSS that is with the cable on the transfer case, it is a two wire device, part of the speedo cable drive.
Not sure of any way to test this for accuracy, it is obviously working or you would have no cruise.

Next would be the "brains", the Speed amplifier, thats where all the wires go and that is what counts the "pulses" from the VSS and then adjusts the servo to maintain the same pulse count when you "set" a speed.
Cruise controls don't know MPH, they all just count pulses, so they need a steady and accurate pulse to maintain a steady and accurate speed

 

Sorry for so long getting back been out of country. Thanks for the info Ill check all listed

 

Anyone have a line on a speed amplifier for 1993 Ranger 4.ol?