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Service bulletin 660421002

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 id606576
Published by NHTSA1999-08-27
Manufacturer's number660421002
Manufacturer's date1999-04-01
NHTSA componentPOWER TRAIN:AUTOMATIC TRANSMISSION:LEVER AND LINKAGE:COLUMN SHIFT

NHTSA's summary

CUSTOMER MAY COMPLAIN THAT THE 4WD IS INOPERATIVE. *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, Automatic transmission

Vehicles listed
CADILLAC ESCALADE1999
CHEVROLET C SERIES1998 to 1999
CHEVROLET DENALI1998 to 1999
CHEVROLET K SERIES1998 to 1999
CHEVROLET TAHOE1998, 1999
CHEVROLET YUKON1998 to 1999
GMC C SERIES1998 to 1999
GMC DENALI1998 to 1999
GMC K SERIES1998 to 1999
GMC TAHOE1998 to 1999
GMC YUKON1998, 1999

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

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.
PIP53462017-08-15. Service bulletin. This Preliminary Information communication provides information to the technician about cooler line fittings that come with the 4T65E General Motors remanufactured transmission may not be the same as Original equipment manufacturer quick connect verses inverted flare. Dealer will need to contact General Motors Technical Assistance Center for further assistance.
3259C2004-03-02. Service bulletin. 4L80E, 4L85E WHINE NOISE IN FIRST AND SECOND GEAR. *TT
010730038B2004-02-10. Service bulletin. THE SERVICE ENGINE SOON LAMP IS ILLUMINATED, NO 3RD AND 4TH GEAR, THE TRANSMISSION DOES NOT SHIFT CORRECTLY, THE TRANSMISSION FEELS LIKE IT SHIFTS TO NEUTRAL OR A LOSS OF DRIVE OCCURS. *TT
020730024A2002-10-11. Service bulletin. DIAGNOSIS OF CRACKED OR BROKEN TRANSMISSION CASE. *TT 2006 AND PRIOR CARS AND LIGHT DUTY TRUCKS. *TT
010730023B2002-10-09. Service bulletin. SOME CUSTOMERS MAY COMMENT ON A HARSH 1-2 UPSHIFT AND THE CHECK ENGINE LIGHT OR SERVICE ENGINE SOON INDICATOR IS ILLUMINATED AND DIAGNOSTIC TROUBLE CODE P1870 SET. *TT
0107300382002-03-25. Service bulletin. SOME CUSTOMERS MAY COMMENT THAT THE SERVICE ENGINE SOON LAMP IS ILLUMINATED, NO 3RD AND 4TH GEAR, THE TRANSMISSION DOES NOT SHIFT CORRECTLY, THE TRANSMISSION FEELS LIKE IT SHIFTS TO NEUTRAL OR A LOSS OF DRIVE OCCURS. *TT
010730023A2002-02-25. Service bulletin. INFORMATION REGARDING HARSH 1-2 UPSHIFT, SERVICE ENGINE SOON, MALFUNCTION INDICATOR LAMP, OR CEL ILLUMINATED, DIAGNOSTIC TROUBLE CODE P1870 SET. (1996-2000 CHEVROLET AND GMC LIGHT DUTY TRUCK MODELS) *YH
0107300232001-10-24. Service bulletin. SOME OWNERS WITH VEHICLES BUILT BEFORE JANUARY 15,1999 MAY COMMENT ON A HARSH 1-2 UPSHIFT AND MAY ALSO HAVE A CHECK ENGINE LIGHT. *ET
010730002D2001-05-29. Service bulletin. MALFUNCTION INDICATOR LAMP (MIL) ON, TRANSMISSION STUCK IN THIRD GEAR, INSTRUMENT CLUSTER INOPERATIVE. *TT UPDATED *EH 2006 AND PRIOR GM PASSENGER CARS AND LIGHT DUTY TRUCKS. *SC