Diagnostic Instructions

•	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.

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
DLC B+	1	1	-	-
DLC Ground	-	1	-	-
1. Scan Tool Does Not Power Up

Circuit/System Description

The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following:

•	Scan tool B+ voltage at terminal 16

•	Scan tool ground at terminal 4

•	Common ground at terminal 5

Diagnostic Aids

•	The scan tool will power up with the ignition OFF. Some modules however, will not communicate unless the ignition is ON and the power mode master module sends the appropriate power mode message.

•	If the B+ circuit, ground circuits, and connections of the DLC are functioning properly, the malfunction must be due to the scan tool.

Reference Information

Schematic Reference

Data Communication Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Testing

1.	Test for less than 2.0 Ω between the ground circuits terminal 4 of the DLC and ground, and terminal 5 of the DLC and ground.

2.	If greater than the specified range, test the ground circuit for an open/high resistance.

3.	Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 16 at the DLC and ground.

4.	If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance.

5.	If all circuits test normal, refer to the scan tool user guide.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.