One problem related to brake master cylinder has been reported for the 2002 GMC Sierra. The most recently reported issues are listed below.
I was driving and my brakes went to the floor. I got it to a repair shop and they said my rear and front drivers side brake lines had rusted out and had holes in them. I had them replaced. Then on February 2013 I had the same problem again. It turned out that now the driver side and the two lines to the master cylinder have rusted through. I have never had a brake line rust through. On this truck I have had to replace everything at the cost of over $500. 00. This is not rite. . . .