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#02-04-21-006E: Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System, DTC C0550 Set No Communication with TCCM (Reprogram Transfer Case Control Module) - (Jul 20, 2006)
|Subject:||Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System, DTC C0550 Set, No Communication with TCCM (Reprogram Transfer Case Control Module)|
|Models:||2004 Buick Rainier|
| ||2002-2004 Chevrolet TrailBlazer, TrailBlazer EXT|
| ||2003-2004 Chevrolet Avalanche, Silverado, Suburban, Tahoe|
| ||2002-2004 GMC Envoy, Envoy XL|
| ||2003-2004 GMC Sierra, Yukon, Yukon XL|
| ||2002-2004 Oldsmobile Bravada|
| ||with Electronic Shift or Active Transfer Case (RPOs NP1, NP4 or NP8)|
This bulletin is being revised to add Subject information and change the labor operation. This bulletin cancels and supersedes Bulletin Number 03-04-21-006. Please discard Corporate Bulletin Numbers 02-04-21-006D and 03-04-21-006 (Section 04 -- Driveline/Axle).
Some customers may comment that the 4WD/AWD indicator lights on the selector switch do not work, or the 4WD/AWD system may be inoperative and/or the service 4WD light is illuminated. The condition is typically intermittent and always occurs at key-up. Upon investigation, the technician may find DTC C0550 set.
The Transfer Case Control Module (TCCM) has not received the wake-up call during key-up and has remained in the "sleep mode".
When the TCCM is in the "sleep mode", it will not communicate with the class II bus or the Tech 2®.
- Try to communicate with the TCCM. If no communication, go to step 2. If communication is possible, go to step 5.
- Remove the underhood (ATCM or TREC) TCCM fuse.
- Wait 30 seconds.
- Reinstall the fuse. The module should "wake up" and communicate with the Tech 2®.
- Check for codes in the TCCM. If a C0550 is found current or in history with or without other codes, replace the module and go to step 6.
- Reprogram the TCCM with the latest TIS software using normal SPS procedures.
- Verify operation and that no codes are present.
Important: For the 2002 model year, the TCCM must be replaced and reprogrammed.