Hi,
Pin 16 in the data link connector should have battery voltage at all times. See pics 1 and 2 below. I also attached the computer data lines schematics. (pics 3 and 4) I had to cut the pic in half to make it readable.
As far as the power supply is concerned, it comes from a fuse under the dash/body control module. See pic 5 for the fuse location. When you check the fuse, confirm there is power to and from it.
Here is a link you may find helpful:
https://www.2carpros.com/articles/how-to-check-a-car-fuse
Also, here is a link you may find helpful as well:
https://www.2carpros.com/articles/comprehensive-guide-troubleshooting-your-automotive-obd2-diagnostic-port
Let me know what you find or if you have questions.
Take care,
joe
See pics below.
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Tuesday, August 29th, 2023 AT 7:56 PM