Pulled ABS fuse, now soft brakes

[SWHeat]

I was checking fuses at random (dumb, I know). Anyway, my son was in the driver's seat and had his foot on the brake. When I pulled the ABS fuse, the brake pedal went to the floor per his report. I did hear a clicking around the master cylinder when I pulled it. I put the fuse back, but now he has soft brakes to the point of the car not being safe to drive. ABS light goes off as usual upon start up.

Did we blow a seal? I tried bleeding the Master Cylinder/ABS system as they are integrated per Haynes manual instructions. No fluid comes out of the rear of the two bleeder valves, weird (which you are to do first). The forward bleeder worked as I would expect with my son working the pedal, but there always seemed to be air in it and the pedal did not firm up despite his desperate hopes. I don't know if bleeding the entire system will help or not.

Any ideas?

 

[chevrofreak]

I've got to say, that seems like a very odd thing to have happen.

I know nothing about this, but if I were in your position my next step would be to disconnect the battery for a few hours.

 

[Gary Allan]

Originally Posted By: chevrofreak
I've got to say, that seems like a very odd thing to have happen.

I know nothing about this, but if I were in your position my next step would be to disconnect the battery for a few hours.


That would be my first next step.

You didn't mention what this is on. While I don't see the need for it with ABS, this WOULD be a situation (no bleed from the back) where a load sensitive proportioning valve were in place (like on a minivan or other FWD vehicle).

 

[SWHeat]

Oops. This is on a 1997 Chevrolet Cavalier (and I thought I did a good job of describing the problem and left out such vital info, embarrassing). Manual transmission (that is why he had is foot was on the brake as we have not fixed his parking brake yet...new to him car two months ago...we just replaced the starter that night that went bad without warning...he learned how to push start his car!!).

Haynes does say to turn to car on for 10 seconds and to wait for the ABS light to go off, then do it a second time to make sure "the ABS pistons in the hydraulic unit...be returned to the top of their travel." I did this, but evidently the rear unit was not up to the top as no fluid would come out of the bleeder last night. Do you have to leave the key in the run position? Nothing mentioned of the like in the Haynes manual.

Also, I had disconnected the battery the night before thinking something may need to be reset. No go. I'll go do it again this AM for the day.

Thanks for the input.

 

[meep]

are the 2 "rear bleeder valves" on the rear brakes or something on the abs module?

This is very odd. if abs fails the car must still be driveable. one of the solenoids is stuck open (there are 2 for each circuit, one closes the valve between the MC and Brk cyl (BC), the other vents BC back into the reservoir. They are normally open and closed, respectively. Sounds like 2nd one stuck open. light tap unit with hammer.

Suspect the fluid is old, has water in it, and rust spots. NEED to flush brake fluid asap.

M

 

[SWHeat]

The two bleeder screws I'm talking about are on the ABS module which is integrated with the master cylinder. There is a rear (which is the lower of the two) that is to be bled first, and a forward one (higher) which is to be bled second. I could get no fluid out of the rear (lower) bleeder screw. I gave up and tried the front (higher) one and it bled as a normal caliper would. I wish I had a picture for you to see.

You are to bleed the master cylinder first, then do the rest of the system if needed.

You are correct about the fluid needing to be flushed, the fluid is not syrup, but dirtier than I would have in my cars.

We will try again tonight as the battery is disconnected at this time for the day.

 

[BuickGN]

If safe to do so, take it out and stand on the brakes to engage the ABS if it has enough brake to do so.