One problem related to brake disc caliper has been reported for the 2004 GMC Sierra 1500. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 GMC Sierra 1500 based on all problems reported for the 2004 Sierra 1500.
2004 GMC 1500 4x4 85,000 mi. , brakes feel soft and have excessive travel during emergency stopping or when towing. Have replaced front pads with more aggressive pads and no help, have tried bleeding several times to no avail. Personally think the problem lies in the lines from the master cyl. To abs box as these are flex style lines not hard lines, I have been in the automotive repair business for 40 years and have not had a problem such as this that I could not locate a problem, all components appear to be working properly, booster, master cyl, abs controller, and calipers. I personally know of several other vehicles from these years with the same problems and gm has not fixed the problems.