D - Brake Pedal Goes Down Fast

D1 CHECK PEDAL FEEL
Road Test vehicle and apply brake pedal.
Was brake pedal effort normal?
YES - Vehicle OK.
NO - Go to D2

D2 CHECK BRAKE FLUID LEVEL
Check Brake Master Cylinder reservoir fluid level.
Is fluid level acceptable ?
YES - Go to D3.
NO - Check Brake Master Cylinder reservoir sealing points. Add fluid and bleed system. Refer to Hydraulic System: Service and Repair for bleeding procedures. Repeat D1.

D3 PRESSURIZE SYSTEM
Pump brake pedal rapidly five times.
Does the brake pedal height build up and then hold?
YES - Bleed air from the system. Repeat D1.
NO - Go to D4.

D4 CHECK FOR BRAKE SYSTEM LEAKS
Check for external brake system leaks. Refer to Hydraulic System - System Diagnosis. Testing and Inspection
Are any found?
YES - Service as necessary, add fluid and bleed system. Repeat D1.
NO - Go to D5.

D5 PERFORM MASTER CYLINDER BYPASS CONDITION CHECK
Perform bypass condition test. Bypass Conditions Test
Was a concern found ?
YES - Replace Brake Master Cylinder. Add fluid and bleed system and repeat D1.
NO - System OK.