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ironmike
ironmike, ASE Master tech
Category: Chevy
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Experience:  30 years ASE Master L1 GM certified
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Chevrolet Suburban 1500 Z71: Have an 03 suburban 1500 4x4 Brake

Customer Question

Have an 03 suburban 1500 4x4
Brake pedal was spongy and would pull to right when I stopped. Replaced front brake lines, calipers, master cylinder (3xs), all new brake pads, rotated rotors, and back brake line. Bled all lines even took it to GMC and had the ABS system bled. Pedal still goes to the floor. Any ideas what is wrong?
Submitted: 1 year ago.
Category: Chevy
Expert:  Eric replied 1 year ago.
HI, Ok, the most common issue is installing the new calipers on the wrong sides - they fit either side but are actually side specific for correct bleeder screw replacement.Look at the calipers you installed. Are the bleeder screws below or above the brake hose to caliper connection?If they are below, then you have them on the wrong side. When the bleeders are below the connection, there is always an air bubble at top caliper that will never bleed out. Swap sides with the calipers and bleed them and you are good to go.If they are correct, let me know and will go from there Please remember to rate service using the rating page so that I may receive credit. ThanksIf for any reason, you can't rate my answer OKAY, GOOD, or EXCELLENT today.Please reply and let me know why, so I can help more/better.All follow up responses are FREE, after completing the required rating
Customer: replied 1 year ago.
The bleeder screws are above
Customer: replied 1 year ago.
Is there a sensor that may have gone bad? Or maybe the abs system?
Expert:  Eric replied 1 year ago.
HI, Ok, we need to do a brake hose clamp test. You will need 4 brake hose clamps. Clamp each of the brake hoses at the wheels. Now test the brake pedal. It should be firm. If the pedal drops to the floor, then with the MC having been replaced and system computer bled, the fault is a bad ABS hydraulic unit with an internal bypass causing loss of pressure. If pedal is firm, then starting at the rear, remove one clamp at a time and retest pedal. At whichever wheel you remove a clamp and the pedal goes to the floor, that is your problem area - either caliper faulty, brake pads cocked at an angle, caliper cocked at an angle, or hose is looped or twisted Please remember to rate service using the rating page so that I may receive credit. ThanksIf for any reason, you can't rate my answer OKAY, GOOD, or EXCELLENT today.Please reply and let me know why, so I can help more/better.All follow up responses are FREE, after completing the required rating
Customer: replied 1 year ago.
Ok we will try that! Is it ok if I get back with you tomorrow on the outcome?
Expert:  Eric replied 1 year ago.
HI,Yes, I am here everyday
Expert:  Eric replied 1 year ago.
I noticed we have not yet resolved your concern you asked about. I would sure appreciate it if you would reply so I can offer my skills and knowledge and repair guide access to help as best I can.~Do you still need more help?~Confused by my info request or answer?~Need more time?~Confused on how the site works?~Need more detail or a different explanation?If the answer is YES to any of these just press reply and lets work on this concern some more.If you have new questions now or in the future please do not hesitate to ask them. If you would like me to assist you. Just bookmark this page so you can access my profile easy and post a new question from the question box on my profile page.Please remember to rate service using the rating page so that I may receive credit. Thanks
Customer: replied 1 year ago.
Tried above and pedal was hard the whole time. Never went to the floor. We bench bled the master again with some extra Chevy lines. That made the pedal a little better. But there's still a good bit of play in the pedal before it actually starts to stop.
Expert:  Eric replied 1 year ago.
HI,Hmm, I am stumped at this point and will open it back up to other experts
Customer: replied 1 year ago.
Thanks again for your help! It has completely stumped us as well.
Expert:  ironmike replied 1 year ago.
Greetings, If there are contaminates stuck in the HCU(hydraulic control unit) it can cause a dump valve to stick open. The HCU is the hydraulic control of the ABS system. I would try first disconnecting the ABS module electrical connector. I have seen a faulty EBCM(electronic brake control module) cause brake to not work properly. If this does not fix the issue I assisted one customer on this site and he removed the ABS assembly and thoroughly cleaned it with brake cleaner and blew it out. I have seen contaminates jam in the HCU and cause poor/low pedals when calipers are pushed back when replacing brakes. It is a lot of work but he did get the brakes working great again and did not replace the HCU. He tried to get a used unit but they did not have it. I would try this since all the things you have already done.

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