# Service bulletin SF636

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: 10201215
- Published by NHTSA: 2021\-09\-28
- Manufacturer's number: SF636
- Manufacturer's date: 2021\-09\-08
- NHTSA component: POWER TRAIN

## NHTSA's summary

Field Service Campaign for Western Star 49X Differential Lock \- Parameter Update. Vehicles may automatically disengage the differential lock without warning when vehicle speed reaches 25 mph.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2021/MC-10201215-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2021/MC-10201215-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Transmission and driveline

## Vehicles listed

- 2021 to 2022 WESTERN STAR 49X

JSON: [/v1/bulletins/10201215](/v1/bulletins/10201215)

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