With Scan Tool

SYSTEM SELF-DIAGNOSIS

In the process of controlling the antilock brake/traction control system, the EBCM monitors operating conditions for possible system malfunctions. Comparing system conditions against standard operating limits, certain circuit and component malfunctions can be detected. A four-digit numerical "Diagnostic Trouble Code" is stored in computer memory when a problem is detected by the self-diagnostic system.

In order to access the diagnostic trouble codes, connect a bi-directional scan tool to the assembly line diagnostic link (ALDL) connector and follow the scan tool manufacturer's instructions to read the diagnostic trouble codes. Once the diagnostic trouble codes have been read and the "ABS/TCS Functional Check" performed, proceed to the "Diagnostic Trouble Code Guide." To clear diagnostic trouble codes after completing repairs, use the bi-directional scan tool and then cycle the ignition switch.

HISTORY VERSUS CURRENT DIAGNOSTIC TROUBLE CODES

The diagnostic trouble codes stored in the EBCM are not specifically designated as "Current" or "History" diagnostic trouble codes, as are PCM diagnostic trouble codes. The amber "ANTILOCK" indicator does however assist in differentiating between current and history diagnostic trouble codes in the following manner.

^ When the amber "ANTILOCK" indicator is illuminated before entering diagnostic mode, at least one diagnostic trouble code is current.

^ When the amber "ANTILOCK" indicator is not illuminated before entering diagnostic mode, no diagnostic trouble code is current.

When more than one diagnostic trouble code is stored and the amber "ANTILOCK" indicator was illuminated before entering diagnostic mode, it is impossible to determine between current and history diagnostic trouble codes.

IMPORTANT

^ When vehicle is equipped with traction control, any symptom which lights the "ANTILOCK" indicator also lights the "TRACTION OFF" indicator. Therefore, when both indicators are lit, follow "ANTILOCK" indicator diagnosis when no diagnostic trouble codes are set.