What should you do if the low air pressure warning signal does not activate after testing?

If the low air pressure warning signal does not activate after testing, checking the air compressor for function is the appropriate step. The air compressor is critical for maintaining proper air pressure in the braking system of a commercial vehicle. If the warning signal fails to activate, it may indicate that the air compressor is not operating correctly, which could lead to insufficient air pressure for effective braking. Ensuring that the compressor functions properly is vital for safety, as it directly affects the vehicle’s braking capability.

In contrast, replacing the brake pads, ignoring the issue, or increasing vehicle speed do not address the potential malfunction of the air compressor and could lead to severe safety risks. Each of those alternatives fails to resolve the underlying problem that could compromise the integrity of the vehicle's braking system.