Help with bleeding ABS Pressure Modulator Valve on 2003 Buick LeSabre

[cabmandone]

Got a feeling I know the answer but.. how do I go about bleeding the pressure modulator valve for the ABS system on a 2003 Buick LeSabre?
My brother had both lines from the master cylinder to the modulator valve go bad. He also replaced the master cylinder. I don't believe he did a MC bleed prior to installation. He used my homemade pressure bleeder to bleed the brakes but the brakes are still spongy. My guess is that he pushed air from the MC and new lines into an ABS valve which is now holding that air. I told him he probably has a valve that needs solenoids cycled which means having a scan tool capable of cycling the ABS. I'm hoping that's incorrect because if I'm right that means I'm getting roped into some work.

BTW, I've done a little searching but don't know how to identify which system the car has.

Thoughts?

[Jeff Hail]

If no accumulator ball is sitting on top of the master cylinder you most likely have a Delphi DBC-7 ABS Unit. Its actually one of the better systems and easy bleeding process.

Assuming you have already bled the four lines to each wheel? You can bleed/purge the abs modulator and see how the pedal feels as well as the height. Its a unique system that has a flow chart path for bleeding so you may have to perform the individual channel bleed again at the end of the process.

Next will require a Scan Tool and Pressurized bleeder for top down transfusion.

Normal bleeding procedures can be used to bleed the individual brake lines provided no air has entered the ABS modulator. But if air has entered the modulator, the system will have to be bled using a pressure bleeder and scan tool:

1.Connect the pressure bleeder to the master cylinder reservoir.

2. Turn the ignition on.

3.With bleeder screws closed, pressurize the system to 35 psi. Have a buddy hold a rag on the pressure bleeder cap because if it blows off in process you will need a new paint job.

4.Select the “Automatic Bleed Procedure” on the scan tool. The scan tool will then energize and cycle the ABS solenoids in the BPMV for one minute.

After this, the scan tool will instruct you to bleed each wheel. During this step, the pump runs and the respective release valve cycles for one minute. This is repeated for each wheel. Finally, the scan tool performs a final 20 second cycling of the ABS solenoids to purge any remaining air.

5. Relieve pressure at the bleed tool and remove it from the master cylinder. Then check pedal height and feel to make sure all the air has been removed and the pedal is firm.

[cabmandone]

Thanks Jeff! I was figuring a scan tool was going to be needed from the reading I've done. My problem beyond the scan tool is that the homemade pressure bleeder won't build 30psi without leaking around the cap on the MC reservoir. My brother might be bringing this thing somewhere to get the job done.

[Bob Kontak]

Originally Posted by cabmando

Thanks Jeff! I was figuring a scan tool was going to be needed from the reading I've done. My problem beyond the scan tool is that the homemade pressure bleeder won't build 30psi without leaking around the cap on the MC reservoir. My brother might be bringing this thing somewhere to get the job done.

I have a scan tool that can fire the solenoids.

I have a Motive Power Bleeder that we could get a GM cap for.

Thanks for the tech info, Jeff.

[cabmandone]

Originally Posted by Bob Kontak

I have a scan tool that can fire the solenoids.

I have a Motive Power Bleeder that we could get a GM cap for.

Thanks for the tech info, Jeff.

I think one of my brothers has the scan tool. I'm checking on that. I'm going to look at the cap I use for my homemade bleeder to see if I can get it to seal better. The cap I use is from a GM vehicle that I modified to work with my pressure bleeder. I'm just not sure it's sturdy enough to hold that kind of pressure.

[cabmandone]

Wanted to say thanks for the tech info. My other brother had a scan tool to cycle the valve and my homemade bleeder did the job! Firm brake pedal achieved. Funny thing though, it instructed me to pump the pedal while the valve was cycling. It was broken down into front circuit and rear circuit. It started with the right front, then left front, right rear, left rear. After each one was bled, it would instruct you to check the fluid level and pressure in the bleeder and then instruct you to open the next bleeder screw, then tell you to pump the brake pedal until the cycle completed.