Crusie control will nit come on all voltage coming fro switch

The crusie control not working would be caused by brake lights being on same as for the key not coming out . You need to test the brake pedal position sensor . The brake pedal position sensor is under the dash hooked to the brake pedal arm . You need a wiring diagram to tell which wires are what . The pedal position sensor isn't like brake light switch from years past , it's an input for the BCM - body control module .There is three wires at the switch , 5 volt ref. , ground and signal . All go to theBCM . You could have a sensor problem , problem with the BCM . There could be DTC'S - diagnostic trouble codes stored in the BCM .
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The body control module (BCM) provides a 5-volt reference voltage and low reference to the brake pedal position sensor. The position sensor provides an analog voltage signal back to the BCM that will increase as the brake pedal is applied. When the brake pedal is applied, the BCM will then apply battery voltage to the left and right stop/turn signal lamp supply voltage circuits and the center high mounted stop lamp (CHMSL) supply voltage circuit illuminating the stop lamps. At the same time the BCM applies battery voltage through the signal circuit to the transmission control module (TCM) and the engine control module (ECM) indicating that the brakes are applied.

Your best bet would bet to take it to qualified repair shop

Take it , it does not set . ? only sets when driving over about 35.
turned on light indicates on in cluster OK.. but will not set, right.??
Dealers go nuts with this one. give them a try.
brake switch on brake peddle arm often fail and go out of ajustment.

Next is big money unit under the hood. Cheaper to bye after market system..

check brake peddle cut out .switch .
sw has 2 functions: brake lights off when at rest and on for crusie. remove connector. check out the switch.. the sw tabs often fail. tierap helps. or replace switch $ 20. item any local parts store.
ajusted on install.

Honestly...There is'nt a fuse for crusie control. Crusie is a function that is controlled by the PCM (Powertrain Control Module)

If the switch is replaced,then it can be wiring issue or faulty cruise control board.But as the switch is replaced,get the voltage at the switch tested to confirm the switch is actually receiving voltage.If no voltage received at switch power supply wire then ,apply external 12 volt power to the cruise control switch wire and then see if cruise control comes ON.If yes,then you know wiring is issue.
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On this case, to troubleshoot this problem, there are solved help links. Click the link directly and refer the details to solve this problem yourself, with help of diagrams: ------

Ford ranger cruise control not working? http://technoanswers.blogspot.in/2012/02/ford-ranger-cruise-control-not-working.html

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Horn and Cruise control quit working?

http://howtobyme.blogspot.com/2011/11/horn-and-cruise-control-quit-working.html

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Horn and cruise control not working on Plymouth Grand Voyager?

http://howtobyme.blogspot.com/2011/11/horn-and-cruise-control-not-working-on.html

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Horn and Cruise control quit working on 2003 Jaguar S-Type?

http://howtobyme.blogspot.com/2011/11/horn-and-cruise-control-quit-working-on.html

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Cruise Control stops working, Excessive cranks to start the engine and RPM goes max 2500

http://whoisbyme.blogspot.in/2012/07/cruise-control-stops-workingexcessive.html

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Cruise control stop working on 1994 Ford ranger?

http://technoanswers.blogspot.in/2012/02/cruise-control-stop-working-on-1994.html

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Cruise control not working?

http://schematicsdiagram.blogspot.com/2011/12/cruise-control-not-working.html

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1996 Ford Explorer: Cruise Control Wiring Diagram?

http://schematicsdiagram.blogspot.in/2012/06/1996-ford-explorer-cruise-control.html

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These will help.

Thanks.

brake sensor switch and clutch pedal sensor switch can be faulty or if automatic , the VSS sensor can be the cause of the problem

Check the fuses and relays.

check brake fluid level.if to low cruise will not work. also check all fuses.

Take your car to Kragen or a parts store like it and have the system tested for codes, also ask them to test your charging system for low voltage, all this is free.

don't use cruise ctl

It sounds like the cruise module is detecting something wrong. I would check the brake pedal switch, it might be out of adjustment or someone might have kicked it by accident.