This study introduces a fuzzy logic-based proportional-integral-derivative (PID) controller that optimizes gain tuning for an electronic parking brake (EPB) system to regulate wheel slip in commercial vehicles. The controller is engineered to operate as a supplementary braking system in scenarios in which the primary brake system fails, achieving stable deceleration by dynamically adjustment of the PD gains. This approach is designed to accommodate varying road conditions and vehicle load states to prevent wheel lock-up and preserve lateral stability. The efficacy of the controller was confirmed via simulation tests conducted under various conditions (e.g., snow and split-surface friction) and extensive vehicle experiments (e.g., snow, ice, and split-surface friction). The findings indicate that the implemented controller provides a robust performance, validating its potential as a reliable secondary braking mechanism for commercial vehicles.