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Service bulletin SIL 839

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 id10203669
Published by NHTSA2021-11-30
Manufacturer's numberSIL 839
Manufacturer's date2021-11-30
NHTSA componentWHEELS; UNKNOWN OR OTHER; EQUIPMENT; POWER TRAIN

NHTSA's summary

Some customers have reported the loss of functionality of the Altec unit or the EZ Trac system on certain 2016-2021 Ford F750 chassis with EZ Trac hydraulic all-wheel drive installed. The investigation has shown that improper wiring could have been installed for the PTO request module that interfaces the EZ Trac system with the Ford system, leading to the loss of functionality. Altec requires the vehicle to be inspected no later than the next preventive maintenance interval or 90 days from the receipt of this SIL, whichever comes first. If the inspection reveals nonconforming operation, the vehicle must be repaired by both an Altec technician and a Terra Drive Systems technician working together. This inspection and repair are covered under the Altec Warranty Policy. The inspection can be performed by Altec, the customer, or the customer’s warranty provider

The document

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

Equipment and accessories, Transmission and driveline, Wheels

Vehicles listed
ALTEC AERIAL DEVICE2016 to 2021

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