BRAKES losing presure! any ideas

[sbsisco]

Bleeding helped but still has the symptoms. not the break light switch, although that was a great suggestion that I haven't thought of. It does find a stopping point about mid pedal so I'm sure your right, its a rear brake issue with the master cylinder....did discover the hard way that it has to be running to bleed the brakes. with it shut off no amount of pumping with push fluid to the calipers....with it running we bled thru each wheel 6-7 times and never really got any air in our fluid recovery line. As supprising as this is, I can find countless h2 master cylinders cheap online but nothing for h3 or colorado trucks. plenty of forums complaining of this issue on colorad truck sites I found tonight. not sure if they share the exact same master cylinder but i did find the caps have the same part no. and thats as far as i got today. the only dealer near me has seen it twice and says nothings wrong so until it has a total failure I guess warranty is out of the question......hmmm..