There are few possibilities that can cause this problem.
Inspect & Check Master Cylinder (For Brake System).A Faulty Brake Master Cylinder can cause this problem.
Inspect & Check Wheel Cylinder.A Worn, Damaged, or Faulty Wheel Cylinder can cause this problem.
Inspect & Check Brake Rotor .If the Brake Rotor Has Worn Past Machining Specifications Then It Must Be Replaced.Or It will cause Brake sinking and fading problem.
Inspect & Check Brake Drum.A Brake Drum Glazed or Excessively Worn then it can cause this problem.
Inspect & Check Brake Fluid Type.The Contaminated Brake Fluid will cause this problem.
Any of this can cause the brake pedal fading or Sinking issue.The spongy feeling brake pedal.Inspecting the mentioned possibilities will help.
This details will help.
Thanks.
See below the Recommended solved problem list:----
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
Replacing ABS unit on Buick Century?
http://technoanswers.blogspot.in/2012/02/replacing-abs-unit-on-buick-century.html
How to Deactivate Airbag system on Ford Ranger?
http://technoanswers.blogspot.in/2012/02/how-to-deactivate-airbag-system-on-ford.html
Brake pedal is pulsating and vibrating?
http://repairhelpcenter.blogspot.com/2012/01/brake-pedal-is-pulsating-and-vibrating.html
All types of brake problems and repairs
What is Brake Drum Bar?
ABS light stays on but brakes work fine?
VCS maintenance required on Toyota Camry?
VCS and ABS lights go on and off intermittently on Lexus?
ABS & Brake lights warning indicator steady on dash and speedometer not working for Dodge Ram?
Isuzu rodeo speedometer is jumping?
http://schematicsdiagram.blogspot.com/2012/01/isuzu-rodeo-speedometer-is-jumping.html
E-brake is stuck down on Ford Focus?
http://schematicsdiagram.blogspot.com/2011/12/e-brake-is-stuck-down-on-ford-focus.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?
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?
How Anti-Lock Brakes Work?
Brake System Troubleshooting?
Car Brake lines have no pressure?
Car Brakes Dragging?
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
How to Disconnect Power to EBCM on
http://schematicsdiagram.blogspot.com/2011/12/how-to-disconnect-power-to-ebcm-on.html
Where is ABS/TCS module located on 2005 Cadillac Deville
http://schematicsdiagram.blogspot.com/2011/12/where-is-abstcs-module-located-on-2005.html
How to Replace Power Brake Booster on 1996 GMC Jimmy?
Isuzu Trooper Shifts hard and Engine Revving in stop?
http://schematicsdiagram.blogspot.com/2011/12/isuzu-trooper-shifts-hard-and-engine.html
What is Brake Bleeder Screw?
http://repairhelpcenter.blogspot.com/2011/12/what-is-brake-bleeder-screw.html
How to replace car Brake Cable?
http://repairhelpcenter.blogspot.com/2011/12/how-to-replace-car-brake-cable.html
How to Replace Brake Disc?
ABS motor keeps running?
http://schematicsdiagram.blogspot.com/2012/01/abs-motor-keeps-running.html
Anti-lock brake light stays on all the time?
http://technoanswers.blogspot.com/2012/01/anti-lock-brake-light-stays-on-all-time.html
Is it necessary to replace Brake caliper while replacing rotors and brake pads?
http://repairhelpcenter.blogspot.com/2012/01/is-it-necessary-to-replace-brake.html
Emergency brake Adjustment for Hyundai Tiburon?
http://schematicsdiagram.blogspot.com/2012/01/emergency-brake-adjustment-for-hyundai.html
How does Brake Backing Plate works?
http://repairhelpcenter.blogspot.in/2012/02/how-does-brake-backing-plate-works.html
How to replace control panel on Audi A4 models?
How to inspect, service and replace brake shoe liner?
How to inspect brake drums?
How to replace Brake light switch on Chevrolet Tahoe?
How to replace brake rotors?
Engine accelerates when brake is applied?
http://technoanswers.blogspot.in/2012/02/engine-accelerates-when-brake-is.html
Loss of acceleration?
http://technoanswers.blogspot.in/2012/02/loss-of-acceleration.html
1996 Chrysler LHS brake light circuit wiring diagram?
http://technoanswers.blogspot.in/2012/02/1996-chrysler-lhs-brake-light-circuit.html
How to replace rear brake pads on 2002
http://technoanswers.blogspot.in/2012/02/how-to-replace-rear-brake-pads-on-2002.html
Brake pedal firm when engine not running goes to floor after engine starts?
http://technoanswers.blogspot.in/2012/02/brake-pedal-firm-when-engine-not.html
How to replace rear Brake lights on 2004 Toyota RAV4?
http://schematicsdiagram.blogspot.in/2012/02/how-to-replace-rear-brake-lights-on.html
Brake drag from wheel area while driving?
http://schematicsdiagram.blogspot.in/2012/02/brake-drag-from-wheel-area-while.html
Brake pedal Pulsating?pulsating.htmlhttp://schematicsdiagram.blogspot.in/2012/03/brake-pedal-pulsating.html
Brake pedal travels excessively?
http://schematicsdiagram.blogspot.in/2012/03/brake-pedal-travels-excessively.html
How To Repair Grabbing Brakes?
http://schematicsdiagram.blogspot.in/2012/03/how-to-repair-grabbing-brakes.html
Inspect & Check Master Cylinder (For Brake System).A Faulty Brake Master Cylinder can cause this problem.
Inspect & Check Wheel Cylinder.A Worn, Damaged, or Faulty Wheel Cylinder can cause this problem.
Inspect & Check Brake Rotor .If the Brake Rotor Has Worn Past Machining Specifications Then It Must Be Replaced.Or It will cause Brake sinking and fading problem.
Inspect & Check Brake Drum.A Brake Drum Glazed or Excessively Worn then it can cause this problem.
Inspect & Check Brake Fluid Type.The Contaminated Brake Fluid will cause this problem.
Any of this can cause the brake pedal fading or Sinking issue.The spongy feeling brake pedal.Inspecting the mentioned possibilities will help.
This details will help.
Thanks.
See below the Recommended solved problem list:----
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
Replacing ABS unit on Buick Century?
http://technoanswers.blogspot.in/2012/02/replacing-abs-unit-on-buick-century.html
How to Deactivate Airbag system on Ford Ranger?
http://technoanswers.blogspot.in/2012/02/how-to-deactivate-airbag-system-on-ford.html
Brake pedal is pulsating and vibrating?
http://repairhelpcenter.blogspot.com/2012/01/brake-pedal-is-pulsating-and-vibrating.html
All types of brake problems and repairs
http://howtobyme.blogspot.com/2011/11/abs-and-service-light-comes-on.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
VCS maintenance required on Toyota Camry?
http://howtobyme.blogspot.com/2011/11/vcs-maintaince-required-on-toyota-camry.html
VCS and ABS lights go on and off intermittently on Lexus?
http://howtobyme.blogspot.com/2011/11/vcs-and-abs-lights-go-on-and-off.html
ABS & Brake lights warning indicator steady on dash and speedometer not working for Dodge Ram?
http://howtobyme.blogspot.com/2011/11/abs-brake-lights-warning-indicator.html
Isuzu rodeo speedometer is jumping?
http://schematicsdiagram.blogspot.com/2012/01/isuzu-rodeo-speedometer-is-jumping.html
E-brake is stuck down on Ford Focus?
http://schematicsdiagram.blogspot.com/2011/12/e-brake-is-stuck-down-on-ford-focus.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
How Anti-Lock Brakes Work?
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
How to Disconnect Power to EBCM on Pontiac Grand Prix?
http://schematicsdiagram.blogspot.com/2011/12/how-to-disconnect-power-to-ebcm-on.html
Where is ABS/TCS module located on 2005 Cadillac Deville
http://schematicsdiagram.blogspot.com/2011/12/where-is-abstcs-module-located-on-2005.html
How to Replace Power Brake Booster on 1996 GMC Jimmy?
http://schematicsdiagram.blogspot.com/2011/12/how-to-replace-power-brake-booster-on.html
Isuzu Trooper Shifts hard and Engine Revving in stop?
http://schematicsdiagram.blogspot.com/2011/12/isuzu-trooper-shifts-hard-and-engine.html
What is Brake Bleeder Screw?
http://repairhelpcenter.blogspot.com/2011/12/what-is-brake-bleeder-screw.html
How to replace car Brake Cable?
http://repairhelpcenter.blogspot.com/2011/12/how-to-replace-car-brake-cable.html
How to Replace Brake Disc?
http://repairhelpcenter.blogspot.com/2011/12/how-to-replace-brake-disc.html
ABS motor keeps running?
http://schematicsdiagram.blogspot.com/2012/01/abs-motor-keeps-running.html
Anti-lock brake light stays on all the time?
http://technoanswers.blogspot.com/2012/01/anti-lock-brake-light-stays-on-all-time.html
Is it necessary to replace Brake caliper while replacing rotors and brake pads?
http://repairhelpcenter.blogspot.com/2012/01/is-it-necessary-to-replace-brake.html
Emergency brake Adjustment for Hyundai Tiburon?
http://schematicsdiagram.blogspot.com/2012/01/emergency-brake-adjustment-for-hyundai.html
How does Brake Backing Plate works?
http://repairhelpcenter.blogspot.in/2012/02/how-does-brake-backing-plate-works.html
How to replace control panel on Audi A4 models?
How to inspect, service and replace brake shoe liner?
How to inspect brake drums?
How to replace Brake light switch on Chevrolet Tahoe?
How to replace brake rotors?
Engine accelerates when brake is applied?
http://technoanswers.blogspot.in/2012/02/engine-accelerates-when-brake-is.html
Loss of acceleration?
http://technoanswers.blogspot.in/2012/02/loss-of-acceleration.html
1996 Chrysler LHS brake light circuit wiring diagram?
http://technoanswers.blogspot.in/2012/02/1996-chrysler-lhs-brake-light-circuit.html
How to replace rear brake pads on 2002 Lincoln continental?
http://technoanswers.blogspot.in/2012/02/how-to-replace-rear-brake-pads-on-2002.html
Brake pedal firm when engine not running goes to floor after engine starts?
http://technoanswers.blogspot.in/2012/02/brake-pedal-firm-when-engine-not.html
How to replace rear Brake lights on 2004 Toyota RAV4?
http://schematicsdiagram.blogspot.in/2012/02/how-to-replace-rear-brake-lights-on.html
Brake drag from wheel area while driving?
http://schematicsdiagram.blogspot.in/2012/02/brake-drag-from-wheel-area-while.html
Brake pedal Pulsating?