Bleeding ABS brakes?

Gordo

Original poster
Member
Mar 26, 2012
81
Need some advice here, changed the brake lines that go from the master to the ABS module. I bled the 4 corners as I would on a non abs unit, got air on two corners, clean fluid on all 4 corners but the pedal will go to the floor if I stand on it. Do I need to activate the ABS pump and rebleed?
The truck is an 05 Silverado, 2500 4x4. 4 wheel discs 6l engine. The truck has some weird system (hydraulic) if front of the master, no vacuum booster as I am accustomed.

Thanks!
 

mrphoenix80

Member
Jan 1, 2013
251
I know the ABS module has an automated bleed you can access with a Tech 2. I don't know if any A/M scan tool will allow this function. If you repalced the lines feeding in to the ABS unit you will need to do this bleed. If you get a tool to acess this you need to "stand" on the pedal durring the bleed. The ABS unit will pump up and release several times. Then you need to rebleed the brakes.

The booster you are describing is known as hydroboost. It uses power steering fluid not vacuum for power. The thing is these systems will allow you to push the pedal farther. I hate bleeding brakes on hydroboost because even after all the air is gone it still feels soft. I never know if it is good until I move the truck and see how it stops. You can pertty much take a good truck and push the pedal 3/4 to the floor.

From my experience if one line is bad the others are not far behind. So check them over good. If you are lucky they will fail while bleeding and not on the road. Also I have been using cooper/nickel allow lines for sometime now and that stuff is WAY easier to work than steel. Another up side is it will not rust.
 

Gordo

Original poster
Member
Mar 26, 2012
81
I do not have a "Tech 2" tool. Can I drive the truck and make the abs work and then rebleed? This will be easy as I have lots of ice in my driveway right now!
 

mrphoenix80

Member
Jan 1, 2013
251
I never tried that. I know the Tech 2 pumps up like 6 times and cycles the valves to release the air. You could give it a shot what the heck. Let me know how it works.
 

gmcman

Member
Dec 12, 2011
4,656
My last boss had a similiar system and I think we raised the truck and turned the steering wheel back and forth many times....15 or more with the engine off. Since the hydroboost uses the P/S pump.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
If air got into the ABS, only a dealer or a shop with a Tech2 can bleed them.
 

tricguy007

Member
Dec 7, 2011
131
A snap-on scanner will bleed them u don't need a tech2
 

Gordo

Original poster
Member
Mar 26, 2012
81
Thanks for all the input! This is what I did. I bled them as normal, put the wheels back on, performed several panic stops on my icy driveway to force the ABS to run. Then I rebled the brakes! Finished!
 

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