Electrical Gremlins

[live2pull]

2004 Yukon Denali
Replaced battery in October of 2018 seemed to be normal replacement due to age of battery (3 years in PHX, AZ)

Replaced battery 2 weeks ago due to a dead cell. Thought nothing of it, possible defective battery.

Replaced battery again this week due to dead cell, however, this time some issues rear their ugly head.

1) No gauge movement other than the Odometer reading
2) no OBD port connectivity
3) radio stays on whether key in ignition or not
4) Start and die condition

Bear in mind this was at 5 am before work so I have not had enough time to trouble shoot this issue. Electrical items I have worked on are the auto ride, added Ebay bypass modules. Replaced TPS connector. And replaced radio.

Current plan when I get some time is check for current draw on battery and associated fuses and double check electrical items I've worked on for issues Other than that I am at a loss on where to proceed. Would a tech 2 help in this situation where there is no connection to the ecm? Any help is appreciated before I have it towed to an electrical shop for diagnosis and possible repair.

 

[Doubeleive]

Check to see if you have power to the drivers side cigarette adapter, if not the fuse is likely popped, that same fuse controls bcm/ecm obd communication, even though the obd port has power it will not have communication if the fuse is popped, just something to check out.

start and die could be a security lock-out see if the security light is flashing with the key on, if blinking do the 10 minute relearn ( key on for 10m 30 seconds, turn key off 30 seconds) then try to start security light should not be flashing.

radio is it's own beast you may have accidentally connected to constant power -check wiring

cluster could be a short, try smacking it, loose solder connections inside are common.

 

[live2pull]

Good News - Truck starts.
Bad news - Haven't figured out why.

Removed radio, tested amp draw; .01 mA.
12V at cigarette lighter, no blown fuse.
Going to reinstall radio and test amp draw. Radio was wired by Crutchfield using their easy wiring service. So it SHOULDN't be mis-wired, haven't had the opportunity to check. I am more inclined to think a piece of wiring rubbed through the insulation and is grounding out. Either, at the head unit wiring, or more likely at the back up camera, that is wired at switched 12v orange wire at the ignition. All trouble shooting is being done 10 minutes before I get into my other vehicle to head to work, or the 10 minutes after I get home before I must go inside to help the wife out with the kids. She is "giving me" Saturday night after bed time to work on it more.

 

[live2pull]

Update:

Been having throttle issues lately, so I opted to change the throttle body.

Before starting I pulled negative battery cable because I replaced the TPS pigtail.

Fast forward an hour to starting the truck, start and die. This time it seemed that the duration of idle was shorter than previous. Still no dash gauges, and no ecu connectivity from obd port. Pulled radio; no change. Pulled negative cable off for a couple minutes. Truck starts. I dont know where to continue from here. And as it was late last night I went in the house.

Is it a grounding issue? Is there a more convenient location for the engine grounds on the passenger cylinder head? I suppose I could test continuity of these grounds.
Is this a sign that the ECU or BCM going bad? Can these be tested?

Any other ideas of what to test?