Description of On-Board Diagnostics

The Rear Anti-lock Brake System (RABS) electronic control module performs system tests and self-checks during start-up and normal operation. The RABS valve, speed sensor, and fluid level circuits are monitored for proper operation. If a concern is found, the anti-lock electronic control module will be deactivated and the REAR ABS light will be illuminated.

Most concerns will cause the light to stay illuminated until the ignition is turned OFF, at which time the anti-lock electronic control module will retain the Diagnostic Trouble Code (DTC) in memory (also referred to as Keep-alive Memory (KAM). Any time the ignition is turned on a DTC may be obtained. A special DTC of 16 indicates that the RABS II system is operating normally. However, there are certain concerns (those associated with loss of power to the anti-lock electronic control module) which will cause the system to be deactivated and the Rear ABS light to be illuminated, but will not provide a diagnostic flashout code.