This bulletin applies to a number of GM vehicles equipped with a 6T30/40/45 automatic transmission, including 2010-2012 Buick LaCrosse, 2011-2012 Buick Regal, 2012 Buick Verano, 2011-2012 Chevy Cruze, 2008-2012 Chevy Malibu, 2010-2012 Chevy Equinox, 2010-2012 GMC Terrain, 2008-2010 Pontiac G8, 2008-2010 Saturn Aura and 2012 Chevy Sonic.
Customers may comment that the SES lamp is on. Technicians may find a current DTC U0101 or the DTC may be stored in history.
Investigation of several vehicles setting DTC U0101 has shown that this condition is frequently caused by issues in areas other than the control solenoid/module assembly (TEHCM).
Prior to any parts replacement, there are several areas that should be inspected. One area is the transmission connector pins, for damaged terminals or poor terminal fit. Another area is the underhood fuse block for damaged terminals or poor terminal fit, and mis-positioned fuses in the fuse block.
Another area to inspect would be the TCM ground. Refer to eSI Automatic Transmission Controls Schematics to determine the ground identification, then the Master Electrical Component List to determine ground location.
As always, powers and grounds should always be load checked to make sure the circuits are able to work properly.
