Scan Tool Does Not Power Up

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 signal ground at terminal 5. The scan tool will power up with the ignition off.

Steps 1 - 4:

Test Description
1. This test verifies that the DLC battery positive voltage circuit is supplying power to the DLC terminal 16.
4. The DLC battery positive voltage and ground circuits are functioning properly. The malfunction must be due to the scan tool.