G 1500 1/2 Ton Van V6-4.3L VIN W (1997)
Brake Master Cylinder: Testing and Inspection
Low Pressure Check
This procedure checks for internal seal damage, porosity and component bore integrity.
1. With the ignition switch in the "OFF" position, pump the brake pedal until all of the power brake booster assist has been depleted (5 times for
vacuum assisted brakes and 25 times for hydraulic assisted brakes).
2. Apply the brake pedal at a slow rate (approximately 1/8 inch per second) to generate pressure in the brake master cylinder and gradually increase
pedal force. Observe for gradually increasing brake pedal travel or the "Falling Away" feel.
a. If the brake pedal tends to fall away. Perform the High Pressure Check. See: High Pressure Check
b. If the High Pressure Check test is good, the brake master cylinder has an internal leak. See: Service and Repair
