I suspect BCM... thoughts?

[sunureu13]

Ooh, we've got new info. I'm pulling U0101 and U0102 codes (lost communication with TCM and Transfer case). Well that would explain the dash errors.

Looks like I've got some deeper inspections to do. I found a longer/more detailed TSB document here: https://static.nhtsa.gov/odi/tsbs/2012/SB-10043829-6448.pdf

So the short version is, every single harness everywhere in the vehicle could have been rubbed through somewhere and everywhere all at once. Yay me.

Anybody want a 2500 suburban? Ugh.

I wrote a big long post while you were posting this. But here's the relevant wiring diagram about what could cause the lost comm with tcm and tc. Those are passed through the bcm.

Again, it could be the bcm getting a bad ground. I'm fairly certain the direct ground for the bcm is on the outside of the frame on the driver's side under the front door, near the cab mount. Small ring terminal. Can get pretty nasty under there especially in snowy places or with fleet vehicles. That ground goes into the harness near it (you'll see it) and I believe that goes up to the junction box. I still need to find my diagrams. I know alldata has them but my subscription lapsed. Might have to resubscribe.

 

[petethepug]

Again, I’ve seen this in another early 07 just a month or two ago. The owner, with close to three decades turning wrenches in the Army, nailed it with the BCM.

There GM Document ID# 2009971 stating the BCM/RAP should have a module reflash.
The cost, $129 for a coded replacement BCM, is much less vs a reflash.

This was the main reason the 07 Esky owner went this route. He just took the same truck from GA to FL last mo on a family vacation.

ARES Technologies No1 Reman Pre-Programmed Engine Computer PCM ECM ECU

If you need an engine computer, we are here to help you to identify the right module for your car.

arestechnologies.com

Keep in mind the BCM controls the smart charging feature of the battery.

This is another interesting clip to follow…

 

[TrybalRage]

I wrote a big long post while you were posting this. But here's the relevant wiring diagram about what could cause the lost comm with tcm and tc. Those are passed through the bcm.

Again, it could be the bcm getting a bad ground. I'm fairly certain the direct ground for the bcm is on the outside of the frame on the driver's side under the front door, near the cab mount. Small ring terminal. Can get pretty nasty under there especially in snowy places or with fleet vehicles. That ground goes into the harness near it (you'll see it) and I believe that goes up to the junction box. I still need to find my diagrams. I know alldata has them but my subscription lapsed. Might have to resubscribe.

I've already wirebrushed that ground connector with no change, unfortunately.

 

[Fless]

Again, I’ve seen this in another early 07 just a month or two ago. The owner, with close to three decades turning wrenches in the Army, nailed it with the BCM.

There GM Document ID# 2009971 stating the BCM/RAP should have a module reflash.
The cost, $129 for a coded replacement BCM, is much less vs a reflash.

This was the main reason the 07 Esky owner went this route. He just took the same truck from GA to FL last mo on a family vacation.

ARES Technologies No1 Reman Pre-Programmed Engine Computer PCM ECM ECU

If you need an engine computer, we are here to help you to identify the right module for your car.

arestechnologies.com

Keep in mind the BCM controls the smart charging feature of the battery.

This is another interesting clip to follow…

The link seems to be for ECM/PCM modules.

 

[TrybalRage]

Keep in mind the BCM controls the smart charging feature of the battery.

This is another interesting clip to follow…

Yep, that video is pretty much what I'm experiencing. Although today, the error just says 4WD, at other times it will say traction/airbag/etc/etc/etc.

 

[sunureu13]

The link seems to be for ECM/PCM modules.

That's just the preview for the link. Pete posted the link to the main site, gotta put in your relevant vehicle information.

 

[sunureu13]

I've already wirebrushed that ground connector with no change, unfortunately.

That's good (and bad).
I went through the troubleshooting in the TSB you linked and it didn't take too long to check for chafed harnesses, bad resistor, loose connectors, etc. Maybe a little more than an hour.

I also reseated all the connectors on the front side of the BCM as well. Once my battery is done charging I will see what happens when I disconnect the bcm or suspension module like in the video. If that "fixes" it, I'm still not 100% sure that means the module is bad or if that could still be a ground issue.
If you want to disconnect the suspension module, I think you have to unbolt it from the frame. At least on my truck (07) the evap canister lines and harness is in the way of the connector.

 

[Rocket Man]

That's just the preview for the link. Pete posted the link to the main site, gotta put in your relevant vehicle information.

Go ahead and try, they don’t list anything for the OP’s vehicle. And they don’t do BCM’s according to that website.

 

[TrybalRage]

That's good (and bad).
I went through the troubleshooting in the TSB you linked and it didn't take too long to check for chafed harnesses, bad resistor, loose connectors, etc. Maybe a little more than an hour.

I also reseated all the connectors on the front side of the BCM as well. Once my battery is done charging I will see what happens when I disconnect the bcm or suspension module like in the video. If that "fixes" it, I'm still not 100% sure that means the module is bad or if that could still be a ground issue.
If you want to disconnect the suspension module, I think you have to unbolt it from the frame. At least on my truck (07) the evap canister lines and harness is in the way of the connector.

I'm fairly certain I don't have a suspension module as I have a 2500 with truck-style leaf springs and traditional shocks. I can still take a look though.

I've already removed and reseated the bcm connectors. I'm also going to clean and check the PCM connectors as well. I've already looked at the transmission connector but did not spend a lot of time inspecting the harness there.

 

[sunureu13]

I'm fairly certain I don't have a suspension module as I have a 2500 with truck-style leaf springs and traditional shocks. I can still take a look though.

I've already removed and reseated the bcm connectors. I'm also going to clean and check the PCM connectors as well. I've already looked at the transmission connector but did not spend a lot of time inspecting the harness there.

You won't have the suspension module, that's only for autoride-equipped models.

I've been through basically everything I could check and it's still pointing towards bad BCM. Pulled all the modules one at a time, checked resistance on pisn 6 & 14 of the obd2 port (should be about 60ohms). Poked around on the BCM connectors to see if there's power (there is). I can communicate with every module except bcm and bcm is still the only relevant dtc I have (checked with tech 2).
I've done basically everything short of checking the wiring diagram and putting probes on each side of every circuit.
Another thing I noticed is that I have low speed bus communication with stuff the BCM controls (windows, locks, hvac, etc) but no high speed bus communication (most notably interior and exterior lights). I still don't exactly know what that means but I'm going from there.

Here's another great resource for this issue:

Schematics, Pinoouts, Training Materials, Technical Documents - PerformanceTrucks.net Forums

Tuning, Diagnostics, Electronics, and Wiring - Schematics, Pinoouts, Training Materials, Technical Documents - We can get GM technical documents if you need then.

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