Why is brake warning light is on - 2004 Ford Expedition

Just add brake fluid as a start. See how long it takes before the light comes on again. Secondly check your brake cylinders for leaks. Lastly but extremely important when was the last time you changed the brakes? Check those brake pads and if you need to change them then do so. Then after changing add brake fluid as required.

It can be issue with master cylinder or the problem is there is still some air there in the system,that has to be bleed.Or else the parts replaced are not aligned properly/.I suggest everything back.

There are few help links mentioned below to troubleshoot the issue.

Click the link below and follow its procedure:-----

2002 Ford Windstar: Brake Warning Light ON dash?

http://schematicsdiagram.blogspot.in/2012/06/2002-ford-windstar-brake-warning-light.html

-----------

Battery and brake Warning lights on Dash
http://alltypesofpartsreplacing.blogspot.com/2012/10/battery-and-brake-warning-lights-on-dash.html
-----------
ABS & Brake warning lights remains steady on dash? http://schematicsdiagram.blogspot.com/2011/12/abs-brake-warning-lights-remains-steady.html
------------

Brake warning light comes on and car will not start intermittently? http://repairhelpcenter.blogspot.com/2011/12/brake-warning-light-comes-on-and-car.html
------------ When the car stops, abs pump turns ON? http://howtobyme.blogspot.com/2011/12/when-car-stopsabs-pump-turns-on.html
----------- Where is Power Brake Booster located on 1995 Lincoln Town Car? http://howtobyme.blogspot.com/2011/12/where-is-power-brake-booster-located-on.html
----------- Sometimes ABS light comes on while Driving?

http://howtobyme.blogspot.com/2011/12/sometimes-abs-light-comes-on-while.html
-----------

All types of brake problems and repairs http://howtobyme.blogspot.com/2011/11/abs-and-service-light-comes-on.html

----------
Brake Fade Issue? http://whoisbyme.blogspot.in/2012/07/brake-fade-issue.html

-----------
Brake System Troubleshooting? http://technoanswers.blogspot.com/2011/11/brake-system-troubleshooting.html

----------
Car Brake lines have no pressure? http://schematicsdiagram.blogspot.com/2011/12/car-brake-lines-have-no-pressure.html

------------
Car Brakes Dragging? http://repairhelpcenter.blogspot.com/2011/12/car-brakes-dragging.html

-------------
Car Brakes grabbing? http://repairhelpcenter.blogspot.com/2011/12/car-brakes-grabbing.html

-----------
Car Brakes Making Noise? http://repairhelpcenter.blogspot.com/2011/12/car-brakes-making-noise.html

-------------
Car Brakes Pulling? http://repairhelpcenter.blogspot.com/2011/12/car-brakes-pulling.html

----------
Pulsating Brake Pedal? http://repairhelpcenter.blogspot.com/2011/12/pulsating-brake-pedal.html

---------
Spongy brake pedal? http://repairhelpcenter.blogspot.com/2011/12/spongy-brake-pedal.html

----------
Hard Brake Pedal? http://repairhelpcenter.blogspot.com/2011/12/hard-brake-pedal.html

------------
Fading Sinking Brake pedal?

http://whoisbyme.blogspot.in/2012/06/fading-sinking-brake-pedal.html

-------------
Feels Like Brake pedal Pulsating http://repairhelpcenter.blogspot.in/2012/06/feels-like-brake-pedal-pulsating.html

-------------
What is Brake Drum Bar? http://repairhelpcenter.blogspot.in/2012/02/what-is-brake-drum-bar.html

------------
ABS light stays on but brakes work fine?

http://howtobyme.blogspot.com/2011/11/abs-light-stays-on-but-brakes-work-fine.html

-----------
Vibrations while braking On Chevrolet Van? http://technoanswers.blogspot.in/2012/04/vibrations-while-braking-on-chevrolet.html

-----------
Dragging brakes? http://howtobyme.blogspot.in/2012/03/dragging-brakes.html

------------
Brake pedal stuck? http://howtobyme.blogspot.in/2012/03/brake-pedal-stuck.html

-----------
After replacing brake rotors and pads, brake pedal remains on floor? http://technoanswers.blogspot.in/2012/02/after-replacing-brake-rotors-and-pads.html

----------
How to replace Brake Power Booster? http://repairhelpcenter.blogspot.in/2012/02/how-to-replace-brake-power-booster.html

-----------
1997 Chevy Tahoe Brake lights not working? http://technoanswers.blogspot.in/2012/02/1997-chevy-tahoe-brake-lights-not.html

------------
How to service Drum brakes? http://repairhelpcenter.blogspot.in/2012/02/how-to-service-drum-brakes.html

-----------
What type of problems usually noticed on Drum brakes? http://repairhelpcenter.blogspot.in/2012/02/what-type-of-problems-usually-noticed.html

----------
How to test Drum Brakes? http://repairhelpcenter.blogspot.in/2012/02/how-to-test-drum-brakes.html

---------
Brake Bleeder Screw Function? http://repairhelpcenter.blogspot.in/2012/02/brake-bleeder-screw-function.html

---------
Toyota Tundra: Parts diagram to replace Brake Drums?

http://technoanswers.blogspot.in/2012/06/toyota-tundra-parts-diagram-to-replace.html
---------- Squeak and grinding sound is heard when brakes are applied?

http://technoanswers.blogspot.in/2012/02/squeak-and-grinding-sound-is-heard-when.html

------------

Brake Pads Inspection on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/brake-pads-inspection-on-acura-integra.html

-------------

How to remove Brake Pads on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-remove-brake-pads-on-acura.html

--------------

How to remove Brake Disc Rotor on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-remove-brake-disc-rotor-on-acura.html

------------

Brake Caliper OVERHAUL on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/brake-caliper-overhaul-on-acura-integra.html

------------

How to remove Brake Caliper on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-remove-brake-caliper-on-acura.html

------------

How to remove Parking Brake shoes on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-remove-parking-brake-shoes-on.html

-----------

How to remove Parking Brake Cable on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-remove-parking-brake-cable-on.html

-------------
Brake pedal is pulsating and vibrating? http://repairhelpcenter.blogspot.com/2012/01/brake-pedal-is-pulsating-and-vibrating.html

----------

These details will help.