Here's the TSB:
-----------------
Malfunction Indicator Lamp (MIL) On, Transmission Stuck in Second or Third Gear, Instrumend Cluster Inoperative (Replace Ignition Switch) #01-07-30-002D - (Oct 19, 2004)
2004-2005 Buick Rainier
1999-2000 Cadillac Escalade
2002-2005 Cadillac Escalade, Escalade EXT
2003-2005 Cadillac ESV
1997-1999 Chevrolet Full-Size Pickup, Suburban, Tahoe (Old Style)
1997-2005 Chevrolet Blazer, Corvette, Express, S-10
1999-2005 Chevrolet Silverado (New Style)
1999-2005 Chevrolet Blazer RH Drive (Export)
2000-2005 Chevrolet Suburban, Tahoe
2002-2005 Chevrolet Avalanche, TrailBlazer, TrailBlazer EXT
2004-2005 Chevrolet Colorado
1997-1999 GMC Sierra, Suburban, Yukon (Old Style)
1997-2001 GMC Jimmy
1997-2005 GMC Savana, Sonoma
1999-2005 GMC Sierra (New Style)
2000-2005 GMC Yukon, Yukon XL
2002-2005 GMC Envoy, Envoy XL
2004-2005 GMC Canyon, Envoy XUV
1997-2004 Oldsmobile Bravada
2004-2005 Pontiac GTO
2003-2005 HUMMER H2
with 4L60-E, 4L65-E, 4L80-E or 4L85-E Automatic Transmission (RPOs M30, M32, M33, MT1, MN
This bulletin is being revised to update model years, add additional models and 4L80/85 Transmission Information. Please discard Corporate Bulletin Number 01-07-30-002C (Section 07 -- Transmission/Transaxle).
Condition
Some customers may comment on one or more of the following conditions:
* The Malfunction Indicator Lamp (MIL) is ON.
* The transmission is defaulted to second gear (4L80/85-E).
* The transmission is defaulted to third gear (4L60/65-E).
* The instrument cluster is inoperative.
Upon investigation, one or all of the diagnostic trouble codes (DTCs) P0740, P0753, P0758, P0785, P0787, P0973, P0976, P1860, P2761, P2764 and P2769 may be set depending on the vehicle.
Cause
The most likely cause of this condition may be a loss of voltage to the transmission on circuit 1020. This loss of power may be caused by an open in the ignition switch. This condition may also be the result of an incorrect installation of an aftermarket electronic device such as a remote starter or alarm system.
Correction
With the ignition switch in the RUN position, test for battery voltage at the IGN 0 fuse (All Av's to date).
If battery voltage is present at the fuse, inspect the ignition voltage circuit between the fuse and the transmission for possible opens. If battery voltage is not present at the fuse, replace the ignition switch using the Ignition Switch Replacement procedure in the Steering Wheel and Column sub-section of the applicable Service Manual. Refer to group number 2.188 of the parts catalog for part description and usage.
If the vehicle is equipped with an aftermarket electronic device and the DTCs are being set when the device is being used, verify that the appropriate fuse listed above is being supplied battery voltage during operation. If voltage is not present at this fuse, these DTCs will be set due to lack of voltage at the solenoids. This condition is most likely to occur with an incorrectly installed remote starting system. If this is the case, refer the customer to the installer of the system for corrections.
-----------------
Document ID# 1556712
Chevrolet Avalanche
Chevrolet Avalanche
Malfunction Indicator Lamp (MIL) On, Transmission Stuck in Second or Third Gear, Instrumend Cluster Inoperative (Replace Ignition Switch) #01-07-30-002D - (Oct 19, 2004)
2004-2005 Buick Rainier
1999-2000 Cadillac Escalade
2002-2005 Cadillac Escalade, Escalade EXT
2003-2005 Cadillac ESV
1997-1999 Chevrolet Full-Size Pickup, Suburban, Tahoe (Old Style)
1997-2005 Chevrolet Blazer, Corvette, Express, S-10
1999-2005 Chevrolet Silverado (New Style)
1999-2005 Chevrolet Blazer RH Drive (Export)
2000-2005 Chevrolet Suburban, Tahoe
2002-2005 Chevrolet Avalanche, TrailBlazer, TrailBlazer EXT
2004-2005 Chevrolet Colorado
1997-1999 GMC Sierra, Suburban, Yukon (Old Style)
1997-2001 GMC Jimmy
1997-2005 GMC Savana, Sonoma
1999-2005 GMC Sierra (New Style)
2000-2005 GMC Yukon, Yukon XL
2002-2005 GMC Envoy, Envoy XL
2004-2005 GMC Canyon, Envoy XUV
1997-2004 Oldsmobile Bravada
2004-2005 Pontiac GTO
2003-2005 HUMMER H2
with 4L60-E, 4L65-E, 4L80-E or 4L85-E Automatic Transmission (RPOs M30, M32, M33, MT1, MN
This bulletin is being revised to update model years, add additional models and 4L80/85 Transmission Information. Please discard Corporate Bulletin Number 01-07-30-002C (Section 07 -- Transmission/Transaxle).
Condition
Some customers may comment on one or more of the following conditions:
* The Malfunction Indicator Lamp (MIL) is ON.
* The transmission is defaulted to second gear (4L80/85-E).
* The transmission is defaulted to third gear (4L60/65-E).
* The instrument cluster is inoperative.
Upon investigation, one or all of the diagnostic trouble codes (DTCs) P0740, P0753, P0758, P0785, P0787, P0973, P0976, P1860, P2761, P2764 and P2769 may be set depending on the vehicle.
Cause
The most likely cause of this condition may be a loss of voltage to the transmission on circuit 1020. This loss of power may be caused by an open in the ignition switch. This condition may also be the result of an incorrect installation of an aftermarket electronic device such as a remote starter or alarm system.
Correction
With the ignition switch in the RUN position, test for battery voltage at the IGN 0 fuse (All Av's to date).
If battery voltage is present at the fuse, inspect the ignition voltage circuit between the fuse and the transmission for possible opens. If battery voltage is not present at the fuse, replace the ignition switch using the Ignition Switch Replacement procedure in the Steering Wheel and Column sub-section of the applicable Service Manual. Refer to group number 2.188 of the parts catalog for part description and usage.
If the vehicle is equipped with an aftermarket electronic device and the DTCs are being set when the device is being used, verify that the appropriate fuse listed above is being supplied battery voltage during operation. If voltage is not present at this fuse, these DTCs will be set due to lack of voltage at the solenoids. This condition is most likely to occur with an incorrectly installed remote starting system. If this is the case, refer the customer to the installer of the system for corrections.