I previously attempted to have my vacuum pump updated on my 2014 sierra after experiencing loss off braking power at very low rpm while parking. Problem was truck was at 73,400 mi. warranty was only up to 72,000 mi. Dealer said call GMC. GMC said (after 3 calls and 2 escalations) no exceptions ! I was Pissed !! Was going to install pump myself but had not got around to it yet. Than new letter came out with 10 year 150,000 mi warranty.
Took my truck in today and dealer replaced pump and performed recall all under warranty. Brakes work really nice at idle and low rpm now. GM should have fixed it on my first request! Oh well its fixed.