Cruise control not working.. 2002 expedition 5.4 lt

This could be one of two things and neither requires a schematic.
1. There is a wire harness inside the steering column called a clock spring. It has to twist every time you turn the wheel. They break.
2. The pads or switches are carbon impregnated rubber and they loose conductivity over time. You can either clean them with alcohol or you can replace them..
The issue is you have to pull the steering wheel off to do some of this and it can require special tools.

At the very least you can check the fuses, if you haven't already. Also, check for applicable trouble codes relating to the cruise control. Around here some of the national brand auto stores will check codes for free. Make sure the brake lamps work.
The diagram is part of the cruise system, if you need the other part holler. I just posted the part with the fuses.

check switch

there should be a relay under the hood or a fuse in the car if those are good then either the switch to turn it on is bad or the cruise control module is bad

Hello there has been a recall on these from ford so it will be worth asking them first to see if yours has been done. Secondly check your brake lights to make sure they are operating correctly,as this can stop your cruise control working. Do you have any warning lights on the dash? Faulty ABS can stop cruise coming on. Also check for any connections for corrosion.

try looking all around the unit for a vaccum leak , it fixed mine

There have been recalls for the cruise controls. Go to a dealer or call with your Vin#. There is a second round of repairs for some year models and the first only involved putting in an additional fuse.

Check the speed sensor at the tranny or near left front tire. Use a manual or find the location on the net. This sensor usually causes problems with the cruise control.

Does Ford replaced the cruise control deactivation switch.
Vehicles involved in the recall include the following:

1998-2002 Ford Ranger
1992-1997 Lincoln Town Car
1992-1997 Ford Crown Victoria
1992-1997 Mercury Grand Marquis
1993-1998 Lincoln Mark VIII
1993-1995 Taurus SHO
1999-2001 Ford Explorer
1999-2001 Mercury Mountaineer
2001-2002 Ford Explorer Sport
2001-2002 Ford Explorer Sport Trac
1992-1993 E150-350 Vans
1997-2002 E150-350 vans
1993-1997 Ford F-Series pickups
1993 Ford Bronco
1994 Mercury Capri
2003-2004 Ford F0150 Lightning
1995-2002 Ford F53 motor homes.

Vehicles involved in the recall include the following:

1998-2002 Ford Ranger
1992-1997 Lincoln Town Car
1992-1997 Ford Expedition
1992-1997 Mercury Grand Marquis
1993-1998 Lincoln Mark VIII
1993-1995 Taurus SHO
1999-2001 Ford Explorer
1999-2001 Mercury Mountaineer
2001-2002 Ford Explorer Sport
2001-2002 Ford Explorer Sport Trac
1992-1993 E150-350 Vans
1997-2002 E150-350 vans
1993 Ford F-Series pickups
1993 Ford Bronco
1994 Mercury Capri
2003-2004 Ford F0150 Lightning
1995-2002 Ford F53 motor homes.