Technical Service Bulletin PIT5480 — 2004 GMC ENVOY

This Preliminary Information communication provides information to the technician about vehicles that intermittently the cruise control is inoperative or that it will not set around or over 70 mph. Technician will need to insure that all four tires are the same size, brand and have similar wear. Verify the Power Control Module and Electronic Brake Control Module tire calibrations are correct. Technician will now check the Instrument Panel Cluster, Power Control Module and Electronic Brake Control Module data for the wheel speeds at 70 MPH or above and write down the difference for each set of speed data. Technician will need to use a Global Positioning System to determine actual speed and compare it to the Power Control Module and Electronic Brake Control Module readings. If the Global Positioning System and Power Control Module speeds match, suspect front wheel hubs and they should be replaced.