A-1 Condition Isolation

^ Block the wheels and apply the parking brake.

^ Place the transmission in PARK or NEUTRAL.

^ Key ON engine running.

^ Disconnect the low-vacuum switch. Run engine at normal idle speed. Apply brakes.

^ Does brake warning light illuminate?

YES -- Condition related to the brake hydraulic system.

NO -- Condition related to the vacuum pump. Go to A2. A-2 Vacuum Pump Output