QUOTE(ClayPerrine @ May 25 2024, 10:09 PM)

Last weekend I put new wheel bearings and brakes in the rear of the 2006 GMC tow vehicle. Took me all day and two trips to harbor freight for tools. Today I put in a new front u-joint, and replaced the front hubs and brakes.
Then we took a trip to Summit racing so I could order AN fittings for the fuel lines on my car. And something in the GMC freaked out. All the gauges lost power, all the idiot lights came on, the radio started giving error codes, and the AC stopped cooling. We got home, and I turned it off and tried to restart it. It wouldn't crank. I pulled the fuse box cover to check for a blown fuse, and while it was open I tried again. It started up.
OBD2 says the body control module and the powertrain control module lost communications. I suspect something like a fusable link causing issues.
And that's why I am not working on all three of our 914s.

Oh well. The AN fittings were not in stock in the Texas warehouse (where I was) and have to be shipped from the warehouse in Ohio.

Update: Today I had a revelation about the Envoy. During the disassembly on the left side, I removed a bolt that I thought held down the wire for the wheel speed sensor. I found out that it was a ground wire. So I tightened it back up.
I spent yesterday evening pouring over the wiring diagrams for the Envoy. This morning, I started thinking about something my father told me when I was 16 and working on my 69 Firebird. I had just replaced the carburetor, and I was trying to get it running. He found me futzing with the timing. He said to me "What was the last thing you F**KED with!?!?" My father normally didn't swear, so it stuck with me. So this morning, I heard my father's voice in my head saying that same phrase. I thought about the symptoms and what I had recently "f**ked with". So I pulled the left front wheel, broke out my Dremel, and cleaned the ground point I disconnected yesterday.
Lo and behold, all of the screwy issues with the Envoy vanished. I took the time enough to clear all the residual codes, and went out for a nice, long test drive. No lights, no gauge issues, and no bonging from the chime module.
The worst part of this is I should know better. On this forum, I always preach the "clean your ground points" mantra before any electrical troubleshooting.

One thing that did crop up. All the intermittent grounding issues killed the AC blend door actuator for the right side. So we have AC on the left, and full heat/defrost on the right. And it is 100 degrees out. I have a new, genuine GM actuator in hand, and early tomorrow morning I will get it installed.
Thanks Dad! I know it didn't seem like it at the time, but I did listen to you.