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Service bulletin T1277

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 id10085583
Published by NHTSA2016-12-06
Manufacturer's numberT1277
Manufacturer's date2012-10-19
NHTSA componentENGINE

NHTSA's summary

THIS TEMPORARY REPAIR PRACTICE ALLOWS THE DRILLING/TAPPING AND INSTALLATION OF A P-CLIP TO THE CYLINDER HEAD IN THE EVENT OF AN ENGINE BRAKE HARNESS FAILURE RESULTING FROM DAMAGE CAUSED BY CONTACT WITH THE ROCKER LEVERS DURING ENGINE OPERATION ON CERTAIN ENGINES.

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

Engine

Vehicles listed
CUMMINS ISX
CUMMINS SIGNATURE

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