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 (Sirius - battery positive voltage) and terminal G (Fenix battery positive voltage). The ground for the scan tool is provided at terminal 4 (Sirius ground DLC) and terminal A (Fenix ground DLC). The 16 pin DLC for the Sirius application provides the serial data signals at terminals 7 (ECM serial data), 8 (Theft Deterrent serial data), 9 (ABS serial data), and 13 (SIR serial data). The 12 pin DLC for the Fenix provides the serial data signals at terminals C (ECM serial data), H (Theft Deterrent serial data), J (SIR serial data), and M (ABS serial data). The scan tool will power up with the ignition off. The ignition must be ON order for the scan tool to communicate with a control module.

Test Description

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

  1. Fuse F11 supplies power to terminal 16 (Sirius) or terminal G (Fenix) of the DLC.

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

Step

Action

Yes

No

1

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

Did you find and correct the condition?

Go to Step 5

Go to Step 2

2

Test the ground circuit of the DLC for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 5

Go to Step 3

3

Inspect for poor connections at the DLC ground terminals and the DLC power terminals at the DLC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 5

Go to Step 4

4

The scan tool may be malfunctioning. Refer to the scan tool user guide.

Did you obtain a properly operating scan tool?

Go to Step 5

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5

Does the scan tool power up?

Go to Diagnostic System Check - Vehicle

Go to Step 1