Although a DRB scan tool is necessary to properly diagnose the ABS system (and is required to access any trouble codes that may have been stored), you can perform a few preliminary checks before taking the vehicle to a dealer who is equipped with this tester.
a). Check the brake fluid level in the master cylinder reservoir.
b). Verify that the electrical connector for the ECU is plugged in.
c). Check the electrical connector at the pump motor.
d). Check the ABS fuses.
e). Follow the wiring harness to each wheel and check that all connections are secure and that the wiring is not damaged.
If the above preliminary checks do not rectify the problem, the vehicle should be diagnosed by a dealer service department or other repair facility equipped with the necessary scan tool. Due to the rather complex nature of the system and the high operating pressures involved, all actual repair work must be done by a dealer service department or other qualified repair shop.