Two problems related to brake light on have been reported for the 2002 Nissan Xterra. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2002 Nissan Xterra based on all problems reported for the 2002 Xterra.
My brakes were losing power with the brake pedal feeling 'mushy' and brake light on. The dealer, maita Nissan, advised me that the spare tire, had rubbed a hole in the brake lining going to the rear brake drums. Nissan did not feel that they were responsible, because the spare tire was oversized, compared to the recommended tire size (sears had installed a wrangler p26570s17 to spare tire compartment on 9/21/2004). Per Nissan, the recommended tire was p266565,17. Fortunately, the loss of hydraulic fluid and loss of braking fluid did not lead to a crash or injury. As you might imagine, as the owner, I did not authorize sears to install the wrong size tire to my vehicle and am certain that they have no idea that the consequence of this error could lead to rubbing a hole in the braking system 4 years later. I requested that the dealer notify Nissan of the incident, and was told that this was not a warranty issue and have no knowledge that other Nissan Xterra se owners will benefit from my experience (the se series came from the factory with a 17 inch custom tire and rim which is a set-up for this type of error and sentinel event).
I have a Nissan Xterra and the wiring to the brake system is faulty. My brake lights went out and I have seen numerous Xterra's all over las vegas of the same year that have the same problem. I went to Nissan about a year ago and they wanted to charge me too much to look at it.