Scan Tool Displays Undefined DTC

CIRCUIT DESCRIPTION
The Electronic Brake Control Module (EBCM) interfaces with a scan tool through terminal 4 via the OBD2 Data Link Connector (DLC) terminal 7. A properly set scan tool connected to the DLC can retrieve ABS diagnostic information like Diagnostic Trouble Codes (DTCs) and perform ABS device control for testing purposes.

DIAGNOSTIC AIDS
Inspect the following list of items when diagnosing this part of the Antilock Brake System (ABS):
^ Scan tool in good working order
^ Scan tool with correct software

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
2. Performs undefined DTC confirmation.
3. Performs undefined DTC confirmation with a known good scan tool.