K2500 ABS Module Help!

[nprice65]

Hi I have a 2000 K2500 ccsb that has a squishy pedal while running. I don’t have access to a scan tool to preform abs bleed. I tried to have my buddy pump the brakes while I press the bleeder on the side of the module but I have absolutely zero fluid coming out. I’m not sure where to go next now.

So far, brand new calipers, rotors, pads, and brake hoses on the front. And brand new shoes, wheel cylinders, and hardware in the rear. Have fluid coming out of all 4 corners while bleeding.

Super firm pedal with the truck off and zero leaks from what I can tell.

Please help! Thanks in advance, I tried searching the forums and didn’t see any threads regarding to no fluid coming out the abs module

 

[someotherguy]

You're really going to need to bleed the ABS unit since you had pretty much everything else open at one point or another to replace all those parts.

It'll probably be worth it to purchase a lower-end consumer grade scan tool that can perform the ABS bleed functions.. or pay a shop to do it. I'd buy the tool. Hopefully someone can chime in with recommendations on an affordable one that is capable; I've got a cheap scan tool that I use for a few things on my GMT800 trucks but I can't recommend it as the reviews seem to indicate it doesn't do much on the older OBD2 trucks in terms of the ABS. I haven't tried it on my trucks either (2006 models)

Richard

 

[nprice65]

So I bought a Autel Maxicheck Pro off Amazon since I found a review saying someone used it on their gmt400.

Cycled the bleed process on the abs module a few times and bled the brakes (pass rear, driver rear, pass front, and driver front) until zero air comes out.

Still have a squishy pedal. What now?

 

[nprice65]

Also I should mention, there was one code that said ABS solenoid was shorted/unplugged. I cleared it and started abs bleeding process and the code never reset. I’m assuming it was due to the abs fuse being unplugged when I first got the truck a few months ago.

 

[Schurkey]

If you're getting air...don't stop bleeding.

Either you're removing the air that was causing the problem, or you've got an air-leak into the system that will have to be tracked-down and repaired.

 

[nprice65]

Zero air coming out when bleeding. I think I’m going to look into the master and booster now.. not sure what else it could be at this point besides replacing all of the hard lines too.

This might sound dumb, but, I know everybody has their opinion on the pedal feel for these trucks; but when the engine is running it should still be a firm pedal correct? My other cars (06 Trailblazer and 17 Equinox) are rock solid.

 

[Schurkey]

Which brake option code does that truck have?

 

[Caman96]

There is a specific procedure.

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Thank @df2x4 for posting this.

 

[evilunclegrimace]

Absent the ablilty to source a scan tool to bleed the brakes find a gravel/dirt road get up to 30 MPH or so and stop hard ,the ABS will /should cycle and possibly move the air out of the moudule and into the systems hard lines.

 

[nprice65]

How do I find the brake option code? Sorry

Thanks I will have to try the 2 man method, I did something similar but I left a few steps out so I’ll give it a shot.

So did some digging and found a trouble shooting guide to diagnose the vacuum booster.. This is after engine was running at idle for a few minutes and then I pressed the brake pedal and released it once. Seems like I have a faulty booster since it’s causing a misfire?

Also when I turn truck off after idling for a few minutes while holding the brake pedal down, it does not stay down. What I was reading said to hold the brake pedal down for 30 seconds after turning the truck off and release, and supposedly they should not move. Mine move instantly even with my foot pressing them down.

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