The On-Board Diagnostic System

THE ON-BOARD DIAGNOSTIC SYSTEM
The brake system is monitored by the controller antilock brake (CAB). The CAB monitors critical input and output circuits within the antilock brake system of the vehicle, making sure they are operating correctly.

Some circuits are tested continuously; others are checked only under certain circumstances.

Each circuit monitored by the CAB has a corresponding diagnostic trouble code (DTC) assigned to it.

^ If the on-board diagnostic system senses that one of the circuits is malfunctioning, it stores the corresponding trouble code in memory.
^ If the malfunction clears after the trouble code is stored, the trouble code will be erased after 50 key cycles, so long as no other DTC's were set within these 50 cycles.