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Service bulletin 4389

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 id10021692
Published by NHTSA2007-06-15
Manufacturer's number4389
NHTSA componentTRAILER HITCHES

NHTSA's summary

TRAILER HITCH INSERT - PRODUCT UPDATE. *KB

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

Trailer hitch

Vehicles listed
CHEVROLET SILVERADO 15002007 (the catalog's model; the bulletin names a series or trim of it)
CHEVROLET SILVERADO 25002007 (the catalog's model; the bulletin names a series or trim of it)
CHEVROLET SILVERADO 35002007 (the catalog's model; the bulletin names a series or trim of it)
GMC SIERRA 15002007 (the catalog's model; the bulletin names a series or trim of it)
GMC SIERRA 25002007 (the catalog's model; the bulletin names a series or trim of it)
GMC SIERRA 35002007 (the catalog's model; the bulletin names a series or trim of it)

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
PIT4729E2023-11-20. Service bulletin. Adding Integrated Trailer Brake Controller RPO JL1.
PIT4729E2017-08-15. Service bulletin. This Preliminary Information communication provides information to the technician about customer's wanting to add the factory Integrated Trailer Brake Controller Regular Production Option Code (JL1) be installed on their Full Size pickup/utility when the vehicle was not ordered with the option. Dealer should advise the customer that if the vehicle does not have the option Regular Production Option Code (JL1) it cannot be added to the vehicle.
PIT4366G2017-08-15. Service bulletin. This Preliminary Information communication provides information to the technician on the steps to diagnose and repair vehicles that may have an intermittent "Check Trailer Wiring" message on the Driver Information Center. Technician will inspect and clean the ground wire (normally white wire) connection on the trailer side of the 7-pin connector. Inspect that the wires inside the trailer side connector are clean and securely fastened. If the vehicle's 7-way connector socket terminals are deformed or have excessive wear, it will be necessary to replace the truck side connector from General Motors Customer Care and Aftersales along with the trailer's 7-way connector plug.