Diagnostic Command Modes

The ABS system includes several self-tests that are performed every time the ignition is turned on and the vehicle is driven away. Some of the self-tests occur immediately, while others do not occur until the vehicle reaches 8 mph.

SELF-TEST AT IGNITION TURN ON
RAM and ROM Checks
RAM and ROM are the two major parts of the microprocessor in the EBC-5H Controller - Antilock Brake (CAB). ROM is a permanent memory that contains the program that performs all computations, makes all logic decisions, and so forth. RAM is an erasable, rewritable memory that is used to keep track of numeric computations and logic decisions as the EBC-5H control program stored in ROM is executed. The RAM and ROM are checked immediately whenever the vehicle ignition is turned on.

Bulb Checks
At ignition turn-on, the CAB also provides the operator of the vehicle with a visual check of the amber ABS warning lamp and the red BRAKE warning lamp. When the ignition switch is turned to the RUN position, the two lamps are turned on for a few seconds. These bulb checks help confirm correct operation of both the CAB and the bulbs themselves. In addition to the visual checks, both lamps are checked by the CAB for circuit failures at this time (as well as at any other time that the lamps are lit by the EBC-5H CAB).

Self-Test at Drive-Off
The system undergoes a power-up self-test when the vehicle first reaches 8 MPH after each ignition turn-on. An active self-test of the ABS system main relay, motor, and the six solenoid valves is performed. The power-up self-tests are abbreviated if the vehicle ignition switch is turned from some other position to RUN above 8 MPH, as might occur in restarting a stalled engine with the vehicle rolling.

DRB DIAGNOSTIC COMMANDS

NOTE: A DRB is a Chrysler Corp proprietary Scan Tool. Most tests can be performed using a different -- suitable -- scan tool and following the scan tool manufacturer's instructions.

Zero-Speed System Test
The zero-speed system test exercises the ABS system. The main relay, pump/motor, isolation and dump solenoid valves are actuated. The CAB monitors these circuits when actuated and will log a failure message if any of these circuits fail to operate properly.

Reset Module
This command resets the EBC-5H system as follows: it turns on both warning lamps, clears all trouble indicators and counters in the NVRAM, and reactivates the system. The reset module command is accepted by the CAB only if the vehicle's wheels are not rotating.