Service bulletin FSB 593 013

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

On some MACK CHU, CXU, GU, and TD truck models built between 04/31/2008 and 11/30/2015, the solenoid valve for the grade gripper feature is prone to internal contamination in harsh environments. The internal contamination of the solenoid valve is caused by the buildup of grime, salt, road debris and other solid contaminants. In some cases, the buildup of solid contaminants caused the solenoid valve to malfunction. A similar malfunction is possible if the solenoid valve is equipped with a vent fitting that freezes over. The malfunction causes the trailer brake circuit to maintain trailer brake pressure after a grade gripper event. Replacement of the existing solenoid valve, elbow, and the addition of a new tube fitting and tube will ensure proper functionality of the grade gripper feature.

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, Equipment and accessories, Wiring and fuses

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

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