2011 Silverado P069E, P0700 - multiple codes - can't find issue

[ctandc]

Just bought this truck used in August for my kid who is normally away at college. No issues first month. Started having an intermittent issue. Here's what happens:

 

Driving down the road, stabilatrak light comes on. Dinging coming from cluster. Speedometer will drop from out and come back. Found the TSB for this intermittent issue (wiring issue somewhere) and pulled the codes. Took it to the Chevy dealer (no friggin warranty of course 2011 with 62K on it.). They pulled the codes but couldn't reproduce the problem. The tech supposedly checked all the noted areas where wiring / connectors could be damaged from TSB. Didn't find any issues. Only charged me 2 hours labor, had the truck all day. Drove @ 30 miles after picking it up, happens again - but now different symptoms and more codes.

 

Stabiliatrak light comes on. Speedometer and tach both dropped out to zero and would not come back. Truck kept running fine. Door locks cycled. If taking off when this happens, from stop, HARD shifts from transmission (TCM losing communication). Pulled the codes with my scan tool:

 

P069E

P0700

U0073

U0101

U0109

U0100

U0073

 

Replaced the battery with new (was original battery) replaced main fuse on positive battery terminal and also installed new GM negative battery cable assembly, making sure chassis grounds were solid. Did this all before taking to shop. Dealership asked if it was okay if tech drove the truck home so he could reproduce the problem (they can't get it to happen, they see the codes buy can't reproduce the issue).

 

Any ideas from the tech's out there?

 

This is a 2WD, 4.8 ext cab short bed. Truck had a leveling kit added when we bought. No hack job. I added GM TPMS sensors after purchase (added new tires) and programmed them without any issues. This started a few weeks later.

 

 

[Sierra_LC9]

 

Did you find a fix for this yet?

 

I bought a Certified Pre-Owned 2010 Sierra SLE 5.3L (LC9) Vin code "3" about 3 years ago. It's stock besides a front leveling spacer on the strut, no aftermarket electrical.
The truck will intermittently go into limp mode with "Service Stabilitrak & Service Traction Control" displayed on the DIC (No SES Light).
Eventually when the CAN bus reboots the SES light illuminates. After clearing the codes it drives normal until it happens again.
I've had it happen on the freeway, in park, on normal surface roads, over bumps, doesn't seem to be a reason why or when it occurs other than outside temps.
The odd thing is it only acts up when its warmer than 60 Degrees outside, this winter she drove fine without a single hiccup. Which tells me it
might be an internal module failure...
However, I've had it happen in the same spot on the way to work several times.
When I pull the DTC's it's from modules that lost communication on the high speed CAN/LAN buss or modules requesting MIL because of no ability to communicate.

DTC's:
U0073 - Communication Bus A OFF
U0100 - Lost Comm with ECM
U0101 - Lost Comm with TCM
P0700 - TCM Request MIL
P069E - Fuel Pump Control Module Request MIL
U0140 - Lost Comm with BCM
U0121 - Lost Comm with EBCM
U0102 - Lost Comm with Transfer Case Cntrl Module

- I've replaced the battery (Optima Red Top), cleaned the terminals and cleaned Mega Fuse. Tested Alternator with a Midtronics GR8
- Cleaned the Grounds on the Front Engine Block, Fire Wall, Chassis under drivers door, front frame by radiator. (Hood to Firewall ground strap missing)
- Removed the UBEC fuse block and swapped relays, no corrosion, applied dielectric grease.
- Removed the TPA lock on the TCM/ Trans connector, checked for backed out terminals or ATF leaking. Found nothing abnormal.
- Checked the Harness from the TCM going up to the Engine Block, nothing abnormal.
- Checked EBCM connectors & harness, nothing abnormal
- Checked FPCM connectors & harness, nothing abnormal
- Replaced 120 Ohm Terminating Resistor (Twice)
- Checked ECM connectors & harness, nothing abnormal
- Checked BCM Connectors, nothing abnormal
- Checked harness on top of engine, nothing
- Using a DLC Break-out box, I have 60 ohms on PIN 14 (CAN High), but haven't been able to test when it acts up.
- I can talk to most modules with my scan tool when the CAN bus is online, if I plug it in just after the bus went down, I cant communicate and have to wait until the bus
reboots to clear the codes and get back on the road. I used to be able to clear the codes "on the fly" while driving but it seems like its taking the bus longer to reboot
as time goes on.
Just ordered new Positive and Negative battery cables, and the Hood ground (not sure why the hood needs a ground)
Could the VCIM module be bad?

The truck is pretty much babied since I've had it, I change the oil myself every 2-3k (fear of AFM issues).

Any help is much appreciated. I'm running out of ideas.