GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The data link connector (DLC) provides operating power for the scan tool at terminal 16 (battery positive voltage) and at terminal 4 (ground). The DLC provides the class 2 serial data signal at terminal 2 and the signal ground at terminal 5. The scan tool will power up with the ignition off.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The CIG/ACCY fuse supplies power to the DLC terminal 16.

  2. The DLC battery positive voltage and ground circuits are functioning properly. The malfunction must be due to the scan tool.

Step

Action

Yes

No

Schematic Reference: Data Link Connector Schematics

1

Test the DLC battery positive voltage circuit for an open or a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Control Module References in Body Control System for the applicable Diagnostic System Check

Go to Step 2

2

Test the DLC ground circuit terminal 4 for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Control Module References in Body Control System for the applicable Diagnostic System Check

Go to Step 3

3

Inspect for poor connections/terminal tension at the DLC terminals 4 and 16. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Control Module References in Body Control System for the applicable Diagnostic System Check

Go to Step 4

4

The scan tool may be malfunctioning. Refer to the scan tool instruction manual.

Did you obtain a properly operating scan tool?

Go to Control Module References in Body Control System for the applicable Diagnostic System Check

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