Vacuum Booster Diagnosis. GMC Truck Yukon Denali 2000

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2000 🢒 Yukon Denali 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Vacuum Booster Diagnosis

Hard Pedal

Checks

Action

Inspect for the following conditions:

•	Broken or damaged hydraulic pipes or hoses

•	A damaged or loose vacuum hose

•	A collapsed vacuum hose

Replace any faulty pipes or hoses.

Inspect for a plugged or loose vacuum fitting.

Clean and correctly tighten the vacuum fitting.

Inspect for the following conditions:

•	A faulty vacuum check valve or grommet

•	Faulty air valve seal or support plate

•	Damaged floating control valve

•	Bad stud welds on the front or rear housing or power head

•	Faulty booster diaphragm

•	Worn or distorted reaction plate or levers

•	Cracked or broken power pistons or retainer

Replace the vacuum booster

Grabby Brakes

Checks

Action

DEFINITION: Apparent Off-On Condition

Inspect for broken or damaged hydraulic brake pipes and hoses.

Replace any faulty pipes or hoses.

Inspect the master cylinder for a low fluid level.

•	Fill reservoirs with the proper brake fluid.

•	Check for leaks.

Inspect the master cylinder for faulty seals.

Repair or replace any faulty seals.

Inspect the master cylinder for a cracked casing.

Replace the master cylinder.

Inspect the following components for leaks:

•	Front calipers

•	Rear wheel cylinders

•

Pipes

•	Connections

Repair or replace any faulty components.

Check the hydraulic system for air.

Bleed the system.

Brakes Fail to Release

Checks

Action

Inspect for the following conditions:

•	A blocked passage in the power piston

•	An air valve sticking shut

•	A broken piston return spring or air valve spring

Replace the vacuum booster.

Inspect for a tight brake pedal linkage.

Repair or replace any faulty component.

Inspect for misadjusted stoplamp or cruise control switches.

Correctly adjust the switches.