G - Brakes Lockup When Applied

G1- Tire Inspection
- Check for excessive wear or tire pressures.
- Check for improper size or type tires.
- Are Tires OK ?
YES - Go to G2.
NO - Substitute known good tires if worn. Inflate to proper pressure. Refer to vehicle certification label on door jam for specification. Go to G2.

G2- Brake Lock-up Test
- Road test vehicle and apply the brake pedal with moderate force on dry, level pavement.
- Do brakes lock-up ?
YES - Go to G3.
NO - Vehicle OK. Service or replace tires as required.

G3- Brake Pad Inspection
- Inspect brake shoes and linings and rotors for grease or fluid contamination, improper linings or wear.
- Are there any concerns ?
YES - Service as necessary and repeat G2. If lock-up is still noted as a result of G2, go to G4.
NO - Go to G4.

G4- Proportioning Valve Test- RH Rear
- Install pressure gauges in LH front and RH rear bleed screws.
- Apply 6895 kPa (1000 psi) to the front system.
- The rear brake pressure must be between 4692-5164 kPa (680-750 psi).
- Is the rear brake pressure within specification?
YES - Inspect disc brake calipers and replace as required then go to G5. Brake Caliper
NO - Replace RH brake pressure control valve and go to G5. Brake Proportioning/Combination Valve

G5- Proportioning Valve Test- LH Rear
- Install pressure gauges on one front and one rear bleed screw.
- Apply 6895 kPa (1000 psi) to the front system.
- The rear brake pressure must be between 4692-5164 kPa (680-750 psi).
- Is the rear brake pressure within specification?
YES - Inspect disc brake calipers and replace as required. Brake Caliper
NO - Replace LH brake pressure control valve. Brake Proportioning/Combination Valve