Service bulletin 21-020-14

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.

NHTSA's summary

Flash: Improved Transmission 5-3 Coast Down Shift Quality This bulletin involves flash reprogramming of the Transmission Control Module (TCM) with new software.Vehicles that are being updated from TCM software p/n 682411$$AA, 682235$$AN or 682354$$AN ($$ are wild cards for any number) will not require the transmission Adaptation Learn Procedure as indicated in Service Bulletin 21-013-13. However, vehicles that are being updated from any other TCM software may require the transmission Adaptation Learn Procedure. Refer to Service Bulletin 21-013-13 for detailed procedures. Failure to perform the procedures outlined in Service Bulletin 21-013-13 on vehicles that were updated from any other TCM software besides p/n 682411$$AA, 682235$$AN or 682354$$AN may result in undesirable shift quality. Customers may indicate that they experience poor shift quality during a 5-3 coast down.

The document

• NHTSA's copy of the document (PDF)
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The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Electrical system, Transmission and driveline

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

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

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