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

TEST DESCRIPTION

Steps 1-4:

The numbers below refer to the step numbers on the diagnostic table.
1. The CIG/ACCY fuse supplies 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.