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GMKindl, ASE Certified Technician
Category: Chevy
Satisfied Customers: 389
Experience:  15 Years Master ASE Certified, ASE Advanced Engine Performance, GM Platinum Pro Service Guild
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Chevrolet K1500 4x4 Brake job soft pedal

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I have a 1998 K1500 4x4 and recently did a brake job on it. I tried bleeding the brakes and even attempted to hold the bleeder button on the brake manifold with no luck on getting the pedal to firm up.  I also used a Snap-On diagnostic tool to make the ABS auto-bleed.  Any advice on what to do next?  The pedal is still not firm, although the brakes do work slightly better than just after I did the brake job.

Hello and welcome to Just Answer. I will be glad to help you find a resolution to your concern, I may ask a few questions to help narrow down the possible solutions. Did you have the soft brake pedal before doing the brake job? What parts did you replace?
Customer: replied 6 years ago.
Did you ever receive my reply with an explanation? I tried sending it the other day.
No, I did not see any post updating the status. I would be glad to help you if you could repost your response.
Customer: replied 6 years ago.

I only had the truck for a short period of time before doing the brake job, and there were problems with the brakes themselves that would have prevented knowing if the pedal was soft from those parts or other problems.


I replaced front pads, calipers, rotors, flexible hoses; rear mechanical drum parts and pads, new pistons, added some new fluid but did not flush system.


After replacing the parts, I worked in the front pads by doing easy stops first and then some progressively harder ones. I did the same for the back and also did the backing up and stopping to reset the ratchet device in the rear drum. I also bled all the air out of the lines when replacing the calipers and pistons. When bleeding brakes I used a home made tool to hold the bleeder button from coming out of the manifold and also used a Snap-On diagnostic tool to auto-bleed the manifold. (Where you hold your foot on the brakes while the computer runs the ABS pump.


Still have vaguely soft brakes when pedal is applied slowly and firm brakes when I slam on the pedal.

The number one cause of a soft brake pedal, especially one that the brake pedal can be pumped and becomes firm, is air in the system. I would first start by bleeding the brakes on last time before condemning any further parts. When you bleed air from the system make sure you start with the right rear, then left rear, then right front, and last the left front. You should be getting new clean brake fluid from each bleeder screw, this may take a few pints of fluid to accomplish. If you are absolutely sure that you have all of the air out of the brake hydraulic system, then I would suspect a failed ABS valve assembly. Your truck is equipped with rear ABS only. What can happen is the ABS dump valve will not hold properly and then allow fluid pressure to bypass the rear brakes and flow into the accumulator. This will result in a low soft brake pedal. To repair this you will need to replace the ABS valve, then you will need to bleed the system again.
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Customer: replied 6 years ago.
Well my dad wants to replace the master cylinder tonight. He thinks it will help with the problem and then we are going to get the autobleed cycle done again in the morning. I will do a thorough bleed on the system after doing the master cylinder but before doing the autobleed. We plan on bench bleeding the master cylinder before installation.