I have 2002 Blazer LS 4wd. I got it it one day and brakes went to floor with very little brake, now it has brake most of the time, but sometimes it just goes to the floor whenever it wants to. I've replaced the master (bench bleed properly) and bleed out all the line started with farthest first, then tried using a vacume bleeder, still no progress, I used 2 big bottles of brake fluid bleeding it with a friend, and still does same thing. I have NO leaks, even took it to the shop to have them bleed out the ABS unit, still acting the same. There is NO "brake" or "ABS" light on. I used my tester and no codes coming up either... engine light wasn't on just thought I would check anyway. I even opened all the bleeders and let it drain out by gravity....still the same. Seams like it does it more often when I back up, but sometimes just driving down the road when I go to hit the brakes it goes to the floor with almost no brakes. But if I release and hit again it seams fine again. Could the module valve be bad? that is what someone told me...never messed with one...is it hard to replace ? Please Help!! Thank you!

 

When you gravity bled the system, did you open the bleeders one at a time or all at once? They must be done one at a time for the gravity bleed procedure to work. Remove the master cylinder cover, open one bleeder valve, allow it to drain until no air bubbles come out of the bleeder valve. Do not allow the master cylinder reservoir to run dry while bleeding. Repeat for each wheel. Depending on how much air is in the system, each wheel might take as much as 10 minutes to complete.

 

Yeah, I let bleed one at a time...never had any air. After that I took to shop to have them bleed it out including the ABS unit with the scan tool. Still the same though. Thanks for the help!

Do you know if the ABS sensor can cause it even if the ABS light is not on? Could that wheel sensor be bad? Seems like it all started around the same time the Rough country suspension kit was put on when I had the upper control arms switched out?

 

There is a GM TSB for ABS activation below 5 MPH and it does not cause the amber ABS light to illuminate. From your description, it didn't sound like the pump came on... or does it?

If the pump doesn't come on, there's an air bubble somewhere, guaranteed. The "Automated bleed" procedure that is done with the scan tool, only bleeds the ABS unit and if there's air elsewhere, the automated bleed will not help. When you bleed each wheel while using the brake pedal, do you get approximately the same pressure out of each bleeder valve?

 

Yes I believe got same pressure...but didn't really take much notice, I'll have a buddy help me out and try it again. about the pump are talking about the abs pump? should it be on when I hit the brakes? I took out the abs sensor on left side and was little grimed up but not to bad, did have couple pieces of metal stuck on it at the end. but cleaned it and still no difference. It seems to do it more often when wheels are turned, but sometimes when I hit the brakes goes almost to floor but still got little bit. just started couple days ago to go 2 floor and very little brake to nun. Still no leaks and fluid level staying full. Do you think I should try Gravity bleed system again? Thanks for the help!

Yesterday I gravity bleed each wheel for 15 min. Always made sure was plenty of fluid in reservoir, bleed one at a time starting with farthest first and so on. Still same problem...Had a friend help me to bleed using pedal each wheel seemed to have the same pressure while bleeding...still the same...??? felt pump on the ABS & wasn't running.. but was just testing with truck in park...when should the pump be working?? When brake pedal is pressed or have to be while stopping??

 

I had a very similar (but worse) problem on my 95. I removed the ABS entirely and am running straight off the master and installed a proportioning valve to the rear line. seems GM's ABS control modules are junk.

 

What condition are your flexible brake lines in? They might be swelling when you apply the brake and absorbing the pressure needed to activate the caliper pistons.

 

I got the S10 2001 SUV and the ABS and Brake light comes on once the engine warms up. Then they stay off till the engine is warmed up again. At one stage my brakes also went to the floor. I did the bleeding thing on all wheels, that kinda helped the brakes going to the floor, but the lights are an ongoing thing. GM had it on the machine and it gave a CO 265 code Motor Relay Circuit. I have bought the GM 3 book manuals, and I am still rattling my brains...Is there any common loose connection problem?

 

Follow the flow chart for C0265, it will take you right to the problem.

 

I own a 2002 blazer and the abs and brake lights come on intermittently. No rhyme or reason. Brake function seems to be normal. Once they light up they will stay on until I shut it off and may or may not come on the next time I start it. Sometimes doesn't come on for a week or so. Any ideas?