GM Service Manual Online
For 1990-2009 cars only

DTC Descriptor

DTC C0900: Device Voltage High

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Description

The electronic brake control module (EBCM) monitors the ignition voltage. If the voltage level is too high, damage may result in the system. When a high voltage condition is detected the EBCM turns OFF the system relay which removes battery voltage from the solenoid valves and pump motor.

Conditions for Running the DTC

Ignition is ON.

Conditions for Setting the DTC

The system voltage is greater than 16 volts for 100 msec.

Action Taken When the DTC Sets

    • ABS disabled if ignition voltage exceeds 19.5 volts.
    • The Antilock Brake System (ABS) indicator turns ON if voltage exceeds 19.5 volts.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

Test the charging system. Refer to Engine Cranks Slowly .