Bizarre ignition/hvac/parking light gremlin

So, I'm battling an odd gremlin and need to get this taken care of as I'm preparing to move a couple thousand miles.

Truck won't start at all if I have the hvac fan on.
Parking lights turn on if the A/C is on.
Tends to stall if I turn the headlights on.
HVAC stays on if I turn the ignition off with parking lights on.
Front turn signals blink together.
ABS light has come on a few times since this started.

I've had my brakes done recently. Some exhaust work. LH lower control arm replaced. Center bearing. Stainless brake lines added.

Maybe @empty_lord can chime in with this one?

 

Sounds like a bad ground somewhere. Try checking the battery terminals and the ground to the chassis from the battery to start. This is one of those problems that is very hard to diagnose without the vehicle in front of you

 

Out of all the work recently done, the exhaust work would be suspect of potentially causing an issue if they were welding on the truck

 

Especially if this was the same shop that snapped his LSPV clean off....

 

Oof, that’s this truck

yea I’d be suspect of work done

 

Can welding cause damage to the integration relay circuits if that and the ECU's weren't disconnected?

 

Are all of these functions controlled by a body control module on the 05-06 trucks? Or traditional relay setup?

 

Thinking out loud….unplug center cluster and see if A/C issues still exist !

 

Progress. I hope.

Tried everything suggested here and went back to check grounds again. I think it might be fixed.

Ground bolt next to the fuse box on the driver side fender was ever slightly loose. Completely missed it the first couple times checking.

Can't believe that would cause so much havoc.

Going to put everything back together and keep my fingers crossed.

 

yea weak grounds can cause all kinds of weird issues as things that use that ground start back feeding trying to find ground.

more load on the circuits that that ground supplies? the more issues you get