On certain trucks, the exterior light switch could fail. If this happens, the hazard lights and the backlight for the instrument cluster display may not work. As a result, warnings, tell-tales and gauges may not display properly.
Safety Risk
Warnings, tell-tales and gauges that don't display properly could increase the risk of a crash. Additionally, hazard lamps that don't work could make the vehicle less visible and increase the risk of a crash.
Corrective Actions
PACCAR will notify owners by mail and advise you to take your truck to a dealership to update the vehicle electronic control unit software.