That post was 15-year-old so we may need to fix again yourselves, here is the problem in question":
"At the same time the "Service Engine Light" came on the "Air bag" light also came on, the overhead lamps don't work, the trunk button quit working. We checked all fuses in three different locations, and none were burned out (under hood, back seat and front passenger seat)."
I have down some research and the BCM is the only component that tries these systems together. If all fuses are good, (key on) this guide can help:
https://www.2carpros.com/articles/how-to-check-a-car-fuse
Then I would check the BCM ground, which is at the right and left kick panels, also I would try a CAN scan which they did not have back then which can help tell you what the problem is. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.
Here is a video to show you how:
https://youtu.be/u-4syLc-ifQ
Here is the location of the BCM so you can check it out, I would check it for water damage. Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.
Images (Click to make bigger)
Saturday, January 4th, 2025 AT 1:00 PM