The UHFB supplies the solenoid circuits with battery voltage when the ignition is in the RUN position. The ABS control module (EBTCM) controls the valve function by grounding the solenoid circuit when necessary.

The #1 solenoids are prime valves. The #2 solenoids are isolation valves.

The DTC will set if the ABS control module detects an open, short to ground or short to voltage on the solenoid circuit(s) inside the control module.

When any of the above DTCs set:

Important: New ABS control modules will automatically set DTC C0551 when installed. To clear DTC C0551, new modules must be configured with the correct engine and transmission option bit. Refer to "ABS Programming" on the Scan tool.

The ABS control module must be replaced.