I have a 96 GMC K 2500 Ext cab short bed, OD AT, 4wd w/ 5.7, all wheel ABS, 125k miles, Brakes are GM option code JB7. The brake system keeps developing air in the lines with no obvious leaks. The master cylinder has been replaced as well as all of the lines on the rear diff. The ABS unit has been disable because it is engaging for no apparent reason when coming to a stop ( I believe that I need to replace speed sensors but I am trying to isolate this problem first). The interim solution is to bleed the brakes at the passenger rear tire up to twice resulting in a temporary resolution. Disc brakes on front, drums rear. Any help would be greatly appreciated.
I believe that there is air still trapped in the abs module that has never gotten out. You can take the vehicle out to a large vacant parking lot, accelerate quickly and slam on the brakes hard to activate the abs. Do this 4 - 5 times. This will move any air trapped in the module into the lines. Then proceed on bleeding the system. Good luck
September, 3, 2007 AT 9:26 PM
I appreciate the suggestion and will try just that.