What must the conditions be when checking power brake pedal travel?

When checking power brake pedal travel, it is essential to have the engine running, as this ensures that the power brake system builds adequate vacuum assistance, which is crucial for accurately assessing the effectiveness of the brake system. Additionally, applying a force of 100 lbs gives a realistic simulation of how the brakes would perform under typical driving conditions. This process allows for the evaluation of the brake pedal's feel and travel, making sure it operates within the manufacturer's specified limits.

Having the engine running provides the necessary power assist that can make a significant difference in pedal resistance and operation. Therefore, this condition ensures that the inspection reflects the actual performance of the brakes under normal operating conditions, thereby leading to accurate results during the inspection process.