One problem related to brake master cylinder has been reported for the 2007 GMC Sierra. The most recently reported issues are listed below.
On oct. 12th,15' while driving on a state highway to the grocery store. As I was slowing down for a red light the pass. Side rear brake line ruptured. To make a long story short I purchased a new brake line and replaced it. I also had to replace the caliper because of corrosion. During the replacement of the brake line I inspected the other brake lines. They were also rusty. I called my service center and they told me it's a result of the pre-treatment solution they spray on the roads in the winter. On Jan. 11th of this year a second brake line ruptured when a car pulled out right in front of me on the same road as before. This time it was the brake line that runs from the master cylinder to the abs module. I purchased this 2007 GMC Sierra 2500hd brand new in Nov of 07'. It has 17,510 original miles. I wash the under carriage every spring as I have on all my previous vehicles. My first chev. Pickup I had for 20 years and never had a brake line issue!! when I talked to the service manager where I have my vehicles serviced he told me they are seeing a lot of pickups coming in with similar issues. He told me that they are installing the new copper/ zinc brake lines which resist the road treatments. When I asked if there's a charge he said for just replacing the brake lines it would be $1,500. Being retired on a fixed income I cannot afford anywhere near that much! being this is a serious safety issue I feel GMC should recall and replace these inferior brake lines. I called gm to ask for help. They told me the only thing they could do is, being a loyal customer, they would give me $2,000 off a new truck if I wanted to trade it in. My response: why would I trade in a truck that's bought and paid for with only 17,510 miles on it and in excellent condition otherwise for another new truck and another 6 years of payments that we cannot afford! please help.