The basic "bumper to bumper" warranty is 48 months (from the in-service date) or 50K miles on the odometer, whichever comes first. Unless this truck was sold to the original purchaser after March 2005 (which is possible, but unlikely), it's not under warranty.
The good news is that this is not always a "Serious" problem. It's often caused by the brake pedal switch which is an easy and cheap DIY fix (search the forum - you'll find detailed instructions).
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