Two problems related to brake hoses, lines/piping, and fittings have been reported for the 1999 GMC C3500. The most recently reported issues are listed below.
Every hydraulic brake line on my 75,000-mile 1999 GMC 3500 pickup has rusted out, and had to be replaced. They all blew out when pedal pressure was applied. . . Including one time, when I was backing up at the transfer station to unload trash. The entire truck could have gone back and fallen into the dumpster.
Contact has 1999 GMC,. He had to replace the brake lines 6 times. The brake lines were corroded. When the brake pedal was pressed the brake line blew out. Contact lost the front brakes on 4 different occasions, and lost rear brakes only once. Vehicle has not been to a service dealer for repairs. Contact has replaced the brake lines with after market equipment.