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Service bulletin 020421006A

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id10000173
Published by NHTSA2003-02-14
Manufacturer's number020421006A
Manufacturer's date2002-10-01
Replaces020421006
NHTSA componentPOWER TRAIN:TRANSFER CASE (4-WHEEL DRIVE)

NHTSA's summary

INOPERATIVE 4WD/AWD LAMPS, INOPERATIVE 4WD/AWD SYSTEM. *TT

The document

No address for NHTSA's copy can be built for this communication. Ask the dealer for it by the manufacturer's number.

Components

Transmission and driveline, Transfer case

Vehicles listed
CHEVROLET AVALANCHE2003
CHEVROLET SILVERADO2003
CHEVROLET SUBURBAN2003
CHEVROLET TAHOE2003
CHEVROLET TRAILBLAZER2002, 2003
GMC ENVOY2002, 2003
GMC SIERRA2003
GMC YUKON2003
OLDSMOBILE BRAVADA2002, 2003

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Recalls for the same vehicles and component
01V3340002001-10-17. POWER TRAIN:TRANSFER CASE (4-WHEEL DRIVE)
01V2830002001-09-05. POWER TRAIN:TRANSFER CASE (4-WHEEL DRIVE)

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
PIP3366C2018-08-20. Service bulletin. This Preliminary information communicates to the dealer technician thatLight Duty Trucks equipped with automatic transmissions and 4 wheel drive may exhibit a condition of grinding/ratcheting type noise when shifting the automatic transmission into park while the transfer case is in 4 wheel drive low (4LO) range. Dealers technician's are advised this condition should be deemed a normal characteristic of 4WD low operation.
36652006-01-25. Service bulletin. 4WD INOPERATIVE AND POSSIBLE DTC C0327 STORED IN THE TRANSFER CASE CONTROL MODULE. *TT
05-04-21-0032005-11-09. Service bulletin. SERVICE 4WD LIGHT ILLUMINATED, DIAGNOSTIC TROUBLE CODE (DTC) C0374 SET. *TT UPDATED 10/05/07. *NJ INSPECT WIRING HARNESS TO TRANSFER CASE SPEED SENSORS, REPLACE WIRING HARNESS. UPDATED 7/18/08 *PE
0404210042005-11-08. Service bulletin. 4WD SWITCH INDICATOR LIGHTS FLASHING, 4WD INOPERATIVE, DIAGNOSTIC TROUBLE CODES C0327, P0550 SET. *TT
34242005-11-02. Service bulletin. ELECTRONIC TRANSFER CASE UNABLE TO COMPLETE SHIFT. *TT
35262005-09-22. Service bulletin. INTERMITTENT SERVICE 4WD LIGHT COMES ON WITH DIAGNOSTIC TROUBLE CODE (DTC) C0306 OR C0308 STORED IN TCCM. *TT
33512005-05-11. Service bulletin. INTERMITTENT MALFUNCTION INDICATOR LAMP (MIL) WITH DIAGNOSTIC TROUBLE CODE (DTC) C0374 OR ERRATIC 4WD/AWD OPERATION. *TT
33492005-05-10. Service bulletin. 4WD INOPERATIVE AND DIAGNOSTIC TROUBLE CODE (DTC) U1026 ATC FUSE OPEN. *TT
3132A2004-11-03. Service bulletin. NVG149 NP3 TRANSFER CASE MAY EXHIBIT A BIND OR SHUDDER ON TURNS. *TC
091320022004-09-30. Service bulletin. THIS MESSAGE COVERS COMMENTS THAT THE SERVICE FOUR-WHEEL DRIVE INDICATOR IS ILLUMINATED OR FOUR-WHEEL DRIVE IS INOPERABLE. *TT