Bulletin No.: 08-07-30-021E

Date: June 07, 2010

Subject: Loss of High Speed GMLAN Communications, Intermittent No Crank, IP Gage Fluctuation, Intermittent Door Lock Cycling, Intermittent Chime Operation, Various IP Warning Lamps Illuminated, Transmission May Not Shift, Communication DTCs U0073, U0100, U0101, U0102, U0109, U0121 or U0140 Set (Repair Backed Out Terminal in Transmission Harness Connector, Repair Open or Shorted GM High Speed LAN Circuits, Open or Shorted Data Link Resistor, Correct Corrosion or Poor Connections in Various Control Module Connectors)
Models:
2007-2010 Cadillac Escalade Models, XLR
2009-2010 Cadillac Escalade Hybrid
2007-2010 Chevrolet Avalanche, Corvette, Silverado, Suburban, Tahoe
2008-2010 Chevrolet Silverado Hybrid, Tahoe Hybrid
2007-2010 GMC Sierra, Yukon Models
2008-2010 GMC Sierra Hybrid, Yukon Hybrid
2008-2009 HUMMER H2

Equipped With 6 Speed 6L80 (RPO MYC) or 6L90 (RPO MYD) or Hybrid Two Mode 2ML70 Automatic Transmission

Please Refer to GMVIS
Supercede:
This bulletin is being revised to update the Parts and Warranty Information. Please discard Corporate Bulletin Number 08-07-30-021D (Section 07 - Transmission/Transaxle).

Condition

Some customers may comment on any of the following conditions:
- Instrument panel cluster (IPC) warning lamps may illuminate.
- The transmission may not shift or defaults to 2nd gear.
- The door locks may cycle by themselves.
- The engine may not crank intermittently.
- A driver information center (DIC) message is displayed.
- The IPC gages may fluctuate.
- Applying the brakes may cause the IPC to become erratic and the chimes to operate simultaneously.

Depending on the vehicle, technicians may find one or more of the following High Speed GMLAN Communications DTCs set as Current or History:
- U0073: Control Module Communications Bus OFF
- U0100: Lost Communication With ECM/PCM
- U0101: Lost Communication With TCM
- U0102: Lost Communication With Transfer Case Control Module
- U0109: Lost Communication With Fuel Pump Control Module
- U0121: Lost Communication With ABS Control Module
- U0140: Lost Communication With Body Control Module (BCM)

Cause

These conditions may be caused by, but not limited to, any of the following:
- The terminal(s) for the High Speed GMLAN Serial Data Bus has backed out of the 16-way electrical connector to the automatic transmission.
- The terminal position assurance (TPA) lock in the transmission 16-way electrical connector is not fully seated.
- The High Speed GMLAN Serial Data Bus circuits are open or shorted to ground.
- Corrosion in various control module connectors.
- Intermittent or poor connections in the inline connectors containing the High Speed GMLAN Serial Data Bus circuits.
- The data link resistor is open or shorted.
- Water intrusion in various control module connectors.