SOLVED - Big 3 upgrade, EVERY warning light on immediately after.

[Tyrant]

Some data from the Tech2 emulator.

 

[Tyrant]

We can add EBCM communication failure to this list, which doesn't surprise me. I'm hoping that these are somehow tied to the auxiliary BCM, although searching that query has been less than useful thus far.

 

[Doubeleive]

We can add EBCM communication failure to this list, which doesn't surprise me. I'm hoping that these are somehow tied to the auxiliary BCM, although searching that query has been less than useful thus far.

There is no aux bcm, mine does the same thing when queried, it may have been some special option at some point or only apply's to some kind of special optional equipment, who knows.
all of the other stuff may be on the same harness, you might start looking for a broken wire or chaffed wire? or maybe the bcm got cooked, just speculating

 

[Tyrant]

Thank you for that, I've been chasing that rabbit hole and it was right up there with the non existent fuel pump fuse/relay fiasco for the 2008 model year!

I've inspected everything that's readily visible, 100% of the wires that I worked with when I changed the battery cables out as well. I've also cleaned and re-seated every ground beneath the body/frame and gone over all quick connects with dielectric grease.

I'm to the point where I'll need to pull the UBEC and the I/P panels, check every single module directly, and re-assemble with dielectric grease now. The Tech2 diagnostic was my last ditch effort to avoid that, since I didn't want to introduce more variables that could exacerbate my problems...

 

[Tyrant]

The BCM would affect all of these, but I'm hesitant to suspect it outright when everything else works... It's a complex system, but I can't help but feel that it's something specific to the wheel speed/hall sensors.

What's frustrating is that those should populate an error other than a failure to communicate, which is what makes me think you're right on the money with the BCM.

 

[Doubeleive]

The BCM would affect all of these, but I'm hesitant to suspect it outright when everything else works... It's a complex system, but I can't help but feel that it's something specific to the wheel speed/hall sensors.

What's frustrating is that those should populate an error other than a failure to communicate, which is what makes me think you're right on the money with the BCM.

a used bcm is not expensive, it's just a mild headache but if you throw a used one in there and program it then it's at least less hassle than chasing wires.
I see in your photos it has no communication with the rear hatch, memory seat, heated seat, etc, so either you don't have any of those? or there is a serious problem

 

[me88]

It IS showing no communication for "Body control module (aux)", which I'm unsure of... Is there an auxiliary BCM? If so, is it tied to the ABS, TCCM, Traction Control, etc?

BCM Aux is only on Export models, like European-market Escalades with Rear Fog Lights.

 

[Tyrant]

a used bcm is not expensive, it's just a mild headache but if you throw a used one in there and program it then it's at least less hassle than chasing wires.
I see in your photos it has no communication with the rear hatch, memory seat, heated seat, etc, so either you don't have any of those? or there is a serious problem

I don't have those, thankfully; it's a moderately optioned LT, I added front heated seats myself but they're a simple relay/switched setup and didn't rely on any other systems.

 

[Tyrant]

The thing I can't wrap my head around is that the 4WD works (minus 4 low), which makes me really suspect the TCCM is functioning but not communicating with the other modules

 

[Tyrant]

I throw it into 4 low once/month to test functionality, so I know it worked prior to this.