This help? I assumed a 1999 L67 was used and brought up the connector information for a 1999 GTP. I'm not sure if there were any year differences without going through year by year.
Looks like the other wire was supposed to be a 12V source. PCM probably provides the ground.
Edit: Found this. Looks like we were right that the 12V source is applied through the connector from the fuse box, and the PCM pin 77 provides the ground.
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