07 Avalanche brake problem
 

I changed my brake fluid in my 07 LS and was being an idiot and let the brake fluid get low in the master cylinder bleeding them out. Now the pedal seems to travel a little further to stop the truck and they feel a bit spongy. I went through 2.5 cans of brake fluid bleeding the system again. They still feel the same, spongy and the pedal travels a little further than what I can remember. When I bled them a third time some air came out and all the fluid was clear. No air came out of the rear brakes, Some air came out of the FR caliper and FL caliper but I let them bleed out a good 4 or 5 times without any air bubbles coming out. Brakes still feel the same. Took it to a mechanic and had him bleed out the system again. Brakes still feel the same. I was wondering if I had to bleed the master cylinder or ABS unit because I let the fluid get low in the master cylinder. What says the forum braintrust??


The ABS light doesnt come on though...

Dealer would be able to do an automated brake bleed with their scan tool. You may still have air trapped in the brake pressure modulator valve(BPMV). I believe some small garages have scan tools that may have that same automated bleed function too. Sometimes what I do after bleeding the brakes on those trucks I drive it around on gravel roads or slippery roads a jamb on the brakes to activate the ABS numerous times which sometimes allows the trapped air to escape back into the resevoir. Works on most occasions, just be sure your somewhere safe while doing this.

Search reverse brake bleeding... Phoenix System.

Honestly it's the best way to do it. I have a high end suction bleeder that I used for years but the Pheonix system just works.

Try driving on a bumpy road to dislodge the air. I had to do that when bleeding the p-car clutch. I had some air trapped, and even the Motive couldn't get it out.

I wouldn't reverse bleed. When you reverse bleed you push all that crap from the calipers through the lines, and abs. The Motive with the Chevy adapter works great on my Tahoe.

Another thing I found doing brakes: Are you sure it's not in your head? I mean, maybe you think the pedals not where it should be because you just worked on the brakes and were looking for job related problems after the service? Kind of hard to explain, but maybe you were expecting a issue, or were looking for soft pedal?

Does anyone else drive the truck? Could you have them see if the pedal feels different than before?