GM Service Manual Online
For 1990-2009 cars only

Diagnostic Information

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC C0901: Device 2 Voltage Low

Circuit/System Description

The electronic brake control module (EBCM) monitors the ignition 1 voltage (IGN1) level available for system operation. A low voltage condition prevents the system from operating properly.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

    •  Ignition 1 (IGN1) voltage to EBCM is less than 6.5 volts for 7 seconds.
    • Vehicle speed is greater than 3 km/h (2 mph).

Action Taken When the DTC Sets

Brake Warning indicator turns ON.

Conditions for Clearing the DTC

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

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Antilock Brake System Connector End Views

Electrical Information Reference

    •  Charging System Test
    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Scan Tool Data List for EBCM

Diagnostic Aids

    • A possible cause of this DTC could be overcharging with a battery charger or jump starting.
    • A high voltage value in multiple modules indicates a concern in the charging system.

Circuit/System Verification

  1. If the DTC is history, refer to Charging System Test .
  2. Start the engine. Record the voltage at the battery terminals. Observe the battery voltage signal parameter in the EBCM data list. Voltages should not differ by more than 1 volt.
  3. If more than 1 volt, replace the EBCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for EBCM replacement, setup, and programming