What is the first step to isolate the air suspension system?

To effectively isolate the air suspension system, opening the brake module cover with a tri key is a critical first step. This action allows access to the internal components of the braking system, which is closely integrated with the air suspension system. By accessing the brake module, technicians can proceed with inspections or modifications necessary for isolating the air suspension.

It's essential to ensure that proper procedures are followed to maintain safety and system integrity, and opening the brake module provides the initial access necessary for further actions, such as checking for leaks or other issues related to the air suspension. This access lays the groundwork for subsequent steps in the isolation process, which ultimately helps in diagnosing and repairing the system effectively.

The other options, while they may be part of the isolation process, do not provide the same foundational access to the necessary components that is gained by opening the brake module.