Cruise Control not working

If anyone with an older Mustang with the Vacuum Servo Cruise Control that is not working and would like to get it working. Might I suggest that before tearing the car apart and contort yourself to check wiring & connections. Check for a blown Fuse and that your brake lights are not blown of course, but also check the Vacuum Dump Valve mounted to the brake peddle. If the valve is out of adjustment or has failed and is leaking the cruise control will not work. This valve is held closed by the brake peddle and will open when the brake peddle is depressed. This valve on later models has been known to become loose in its mounting bracket and go out of adjustment over time.

A quick and easy way to verify the valve is holding vacuum without removing the valve from under the dash is by doing the following using a simple tool such as a syringe, vacuum hand pump, or even a turkey baster to place the line between the valve and servo under a vacuum.
1: Remove the vacuum line from the servo to the dump valve
2: Insert the syringe with the plunger fully inserted into the tube and attempt to pull the plunger out. If the plunger moves out easily the valve is leaking. If a vacuum pump is used air will be heard leaking under the dash. If using a turkey baster the suction bulb will expand as air is drawn in or remain compressed if tight
If the valve is leaking it may be possible to reseal the valve by adjusting the position of the valve with following steps
1: Reach up under the dash to find the valve and wiggle it while pushing the valve toward the brake peddle. You will hear an audible click as the adjustment ring on the valve passes through the spring retainer clip
2: Check the line again with the syringe to see if there is more resistance
3: Continue top adjust the valve 1 or 2 notches at a time and check the line for vacuum until you can no longer pull out the plunger of the syringe or the pump and or baster indicates the line holds a vacuum. If after doing doing 3 or 4 valve adjustments, the valve still doesn't hold a vacuum, the valve has probably failed and needs to be replaced
4: Reconnect to the vacuum line to the servo and go for a drive to test the cruise control.

If the vacuum test prove the valve holds a good vacuum and the cruise still does not work you are stuck with going under the dash to find the bad connection or switch
 
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