# Service bulletin 990421003

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.

- Type: Service bulletin
- NHTSA id: 606091
- Published by NHTSA: 1999\-08\-06
- Manufacturer's number: 990421003
- Manufacturer's date: 1999\-06\-01
- NHTSA component: POWER TRAIN:TRANSFER CASE \(4\-WHEEL DRIVE\)

## NHTSA's summary

SOME OWNERS MAY COMMENT ABOUT A SLIPPING TYPE CONDITION AT THE FRONT WHEELS WHILE THE VEHICLE IS IN FOUR WHEEL DRIVE \(4WD\). \*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

- 1999 CHEVROLET BLAZER
- 1999 CHEVROLET ENVOY
- 1999 CHEVROLET JIMMY
- 1999 CHEVROLET K SERIES
- 1999 CHEVROLET SIERRA
- 1999 CHEVROLET SILVERADO
- 1999 CHEVROLET T SERIES
- 1999 GMC BLAZER
- 1999 GMC ENVOY
- 1999 GMC JIMMY
- 1999 GMC K SERIES
- 1999 GMC SIERRA
- 1999 GMC SILVERADO
- 1999 GMC T SERIES

## Other bulletins for the same vehicles and component

- [PIP3366C](/bulletins/10143757.md), 2018-08-20, Service bulletin: POWER TRAIN:TRANSFER CASE \(4\-WHEEL DRIVE\); POWER TRAIN:AUTOMATIC TRANSMISSION. 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\&\#39;s are advised this condition should be deemed a normal characteristic of 4WD low operation.
- [3424](/bulletins/10017299.md), 2005-11-02, Service bulletin: POWER TRAIN:TRANSFER CASE \(4\-WHEEL DRIVE\). ELECTRONIC TRANSFER CASE UNABLE TO COMPLETE SHIFT. \*TT
- [3389](/bulletins/10016707.md), 2005-09-28, Service bulletin: POWER TRAIN:TRANSFER CASE \(4\-WHEEL DRIVE\). FOUR WHEEL DRIVE INOPERATIVE AND THE 4WD SERVICE LIGHT WILL ILLUMINATE. DIAGNOSIS MAY REVEAL THAT THE ATC FUSE COULD BE OPEN, POSSIBLE DTC C0308, OR VARIOUS U CODES MAY BE SET. THE ENCODER MOTOR MAY ALSO BE SHORTED OR THE TCCM MAY BE DAMAGED. \*TT
- [3526](/bulletins/10016558.md), 2005-09-22, Service bulletin: POWER TRAIN:TRANSFER CASE \(4\-WHEEL DRIVE\). INTERMITTENT SERVICE 4WD LIGHT COMES ON WITH DIAGNOSTIC TROUBLE CODE \(DTC\) C0306 OR C0308 STORED IN TCCM. \*TT
- [3349](/bulletins/10014809.md), 2005-05-10, Service bulletin: POWER TRAIN:TRANSFER CASE \(4\-WHEEL DRIVE\). 4WD INOPERATIVE AND DIAGNOSTIC TROUBLE CODE \(DTC\) U1026 ATC FUSE OPEN. \*TT
- [3012B](/bulletins/10008806.md), 2004-08-23, Service bulletin: POWER TRAIN:TRANSFER CASE \(4\-WHEEL DRIVE\). THE NVG 136 ALL WHEEL DRIVE \(AWD\) TRANSFER CASE AND THE 236 AND 246 NVG SELECTABLE TRANSFER CASES OPERATING IN THE AUTO MODE MAY EXHIBIT A CONDITION OF A VIBRATION/SHUDDER DURING LOW SPEED TURNS SUCH AS A PARKING LOT MANEUVER, UP TO APPROXIMATELY 5 MPH. \*TT 3012A NOT YET RECEIVED. \*TT
- [01409](/bulletins/10004212.md), 2003-11-22, Service bulletin: POWER TRAIN:TRANSFER CASE \(4\-WHEEL DRIVE\). THE NVG 136 ALL WHEEL DRIVE \(AWD\) TRANSFER CASE AND THE 236 AND 246 NVG SELECTABLE TRANSFER CASE SHUDDER ON TURNS. \*TT
- [020421004](/bulletins/634899.md), 2002-10-10, Service bulletin: POWER TRAIN:TRANSFER CASE \(4\-WHEEL DRIVE\). SOME CUSTOMERS MAY COMMENT ON THE SERVICE 4WD INDICATOR ILLUMINATING WITH DIAGNOSTIC TROUBLE CODE B2725 SET. \*TT

JSON: [/v1/bulletins/606091](/v1/bulletins/606091)

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