Which of the following should be done before putting a vehicle "Out of Service" due to slack adjuster issues?

Putting a vehicle "Out of Service" due to slack adjuster issues is a necessary safety protocol, and the process begins with stopping and parking the vehicle. This is crucial because a vehicle must be stationary and in a secure location before conducting any further evaluations or adjustments. Stopping and parking ensure not only the safety of the operator but also that of anyone in proximity to the vehicle.

Once the vehicle is safely parked, further steps such as notifying maintenance, checking tire pressure, or performing visual inspections can be carried out effectively and safely, allowing for a thorough assessment of any issues without risking injury or additional vehicle damages. Stopping the vehicle precedes all other actions because it provides a safe environment to address the slack adjuster concerns.