Front brake lock up

Tiny
PAUL ALLRED
  • MEMBER
  • 1996 CHEVROLET 1500
  • 5.7L
  • V8
  • 4WD
  • MANUAL
  • 210,000 MILES
I have replaced both rear wheel cylinders/brake lines to rear axle, all new emergency brake cables/both front rotors, shoes, calipers, and rubber line from calipers. Both master cylinder and booster. I bench bleed master, bottle bleed, the whole brake system six times. I do have a new ABS pressure modulator switch on the way. Brakes are great before starting truck. Once truck is started if you press the brake pedal pedal sticks to the floor. I have disconnected the ABS, fuse and wires to no difference. My guess is air in ABS. The kicker is, I can hook up code reader/scanner to aldl and nothing. It powers up and say everything is good and I know better. Even tested the scanner against another vehicle. It works properly. I am looking for an aldl pin out wiring diagram so I can make an attempt to read adld to diagnose ABS. Any suggestions other than slamming my hand in the door?
Sunday, December 30th, 2018 AT 2:00 AM

3 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

The ABS module needs to be bled with a scan tool. there is most likely air trapped in the module.

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

You need to hook up the scan tool and access the brakes in the menu. Then go to functional tests and then to brake bleeding. there will be a procedure to follow for bleeding the ABS unit.

You may need to do this a couple times to get the air out of the system.

If you do not have a scan tool, any shop with a scan tool can do this procedure for you.

Roy

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Friday, April 9th, 2021 AT 2:18 PM
Tiny
PAUL ALLRED
  • MEMBER
  • 12 POSTS
That's what I figured. The thing about the aldl port? Brake light does come on when key is turned and goes back out. Shouldn't there be some type of ABS code or something being thrown out to the adld?
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Friday, April 9th, 2021 AT 2:18 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
If there is a fault stored, yes.

When you turn on the key the yellow ABS light should come on and then go off.

The red brake light will come on in the start position as a bulb check.

Roy
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Friday, April 9th, 2021 AT 2:18 PM

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