You are doing a pre-trip inspection on a tractor-trailer and notice the trailer's ABS malfunction lamp stays on after the startup bulb check. What does this indicate, and what should you do?

AAMVA CDL Manual, Section 5, subsections 5.1.16 (p. 5-4, lamp location and bulb-check behavior) and 5.4.2 (p. 5-8, 'drive normally, but get the system serviced soon'); Section 6, subsections 6.3.1 (p. 6-7, 'Trailers Required to Have ABS') and 6.3.2 (p. 6-

Recognizing a real ABS fault versus normal startup behavior keeps you from either assuming your regular brakes are also gone or ignoring a genuine problem that needs repair. Pre-trip and en-route inspections specifically test whether you can read these malfunction indicators correctly.