Okay this might be a little lengthy so please bare with me.

I have a 2001 Jimmy, when I bought it the front calipers were rusted open, so I went ahead and replaced all four calipers, I also replaced the master cylinder and flushed / bled it all.

Brakes work but they're a little spongy and bleed down at while stopped; I re-bled it all, checked vacuum at the booster and I am at a loss.

I work at a big auto parts supplier (largest in the country) and we have our own master techs who said it might be that I got air in the ABS Modulator Valve and it would need to bled out. They all said to just take it to a shop and have them hook it up to the computer and run it through the module valve purge program.

My question to you guys is, does anybody know how to to this without taking it to a shop?
(because I'm a cheap bastard)

Any help would be greatly appreciated

 

I have never personally experienced this issue. However, from what I understand, if you have air in the ABS, it has to be fixed by a shop with the proper computer equipment.

 

Find a deserted gravel road and carefully get creative...

 

Tajohns34, yah that's what I've been hearing, I was hoping there was a way to do it ourselves, I hate to fork out $60 for a shop to do it if there is an OBD way to do it.

 

CWBDDSPC, could you explain?

 

The automated bleed process activates the abs module numerous times to move the fluid and any air bubbles through. So, if one does not have a device such as a tech2 scanner to perform an automated bleed, how else might one be able to activate the abs module? My driveway is gravel as is my staff parking lot at work. Before I purchased my tech2, I just hits the brakes numerous times in my parking lot to bleed the abs module. Now obviously you DO NOT want to do this somewhere that might cause a collision and you don't need to go very fast prior to applying the brakes. Activate the abs a handful of times and then rebleed the brakes. You should be all set after that. Bleeding these things can be tricky too. Lots of threads exist on how to best do it. To sum them up gravity bleed the system first, then bleed regularly if still needed. Don't let the fluid run dry!

 

***UPDATE***
So I had the modulator valve run though the bleed/purge program, problem still there.
Changed out pads/rotors (already had them was just being lazy), problem still there.

So the brakes work, they "bleed down", and when stomped for quick stop the ABS works but sounds like a frik'n Elk.

So here's what I've done so far:

New master cylinder
New calipers
New rotors
New pads
Booster vacuum checked
lines & hoses checked, no likes or bulges
System, including modulator valve, flushed and bled

ANY ideas?
Maybe bypass ABS and try?
Take it to a dedicated brake shop?

 

I'm assuming your ABS light isnt on, right?

There was one blazer i worked on in which the brake pedal was an issue.

also, blazers have aged by at least 13 years now....my own blazer was one of the last ones made in 2004

what im saying is, with age some parts are gonna develop a certain amount of "play"...besides the brake system...theres the steering wheel, sounds the engine makes even after maintenance is made on time, the way the rocks back an inch after shifting to park, oh and the way a simple door can swing open

some of these issues can be tightened, replaced or fixed...but if not its just old age, like wrinkles lol

Oh last thing i just thought of, there have been people known to forget to put their brake fluid cap back on at time...dirt and debris get in those lines and can add to that compressible spongyness...i heard that from a tech at chevy, he blows compressed air thru the lines somehow....I've never heard of this before, but i guess

 

No codes, no ABS light.
This is just more than an old truck; sometimes the brakes go all the way down when stopping, not good.
I guess I'll have to break down and take it to a shop that does nothing but breaks and have them do complete system diagnostic.