Archived Brakes ABS light... low pedal pressure

[MBurke]

My 97 has had the ABS light and the brake light coming on for about a month now. Today on a return trip for Maryland, the lights came on and did not go out when the truck was turned off and restarted like they usually do.

They have been on for the remainder of the trip... about 400 miles. When I got home I noticed that if I step or basically stand on the brake pedal, that it will start to sink slowly toward the floor. While it is slowly going down, you can hear a noise. If you continue to push very hard, the pedal will slowly depress to the floor while making noises. (hissing???)

Unsure if I have 2 unrelated problems, or just one big one.

When I looked under the hood at the relay box, there is a socket that is marked ABS light that does not contain a relay... . should it???

My main concern is with the brake pedal going down. Please correct me if I am wrong, but I always thought that it should depress a small amount and then be like pressing on a rock with no sponging or noise.

The brakes feel pretty normal without the trailer and without, I just can't imagine that the pedal should sink like that. (It does require quite a bit of pressure to get it to sink). And I am certain the ABS and brake lights should not be on.

Please help, I am supposed to take another run this week, but the brake thing has me a little scared. (Please see signature for truck info)

Thanks in advance,

Mike.

 

[Larry Willard]

Sounds like the master cylinder is gone. Don't know if that will cause the ABS light to come on, but in the old days it would cause the brake light to come on.

Larry

 

[Joe Mc]

My vote is on the master cylinder too. The hiss you hear is most likely the fluid bleeding by the piston when you push down, hence the seeping slowly to the floor/hisss. As far as the ABS ? Could be lack of pressure to the rear system? Your sig didn't indicate "all wheel" or just "rear" ABS. Either way it "could" be related. Also, either way with all the goodies you have invested in your rig and all the weight you will probably be hauling on your next scheduled "run", instead I would "schedule" what sounds like your rig is trying to tell you needs attention first. MHO - If it was me I'd listen to the hiss and think of what mattered most - the next run or being able to stop the run afterwards. Better yet not being able to stop during any "run". :{ #@$%!



Hate to be a kill joy and all, but this could be one of those very BIG pay me now or laters. It's totally your call of course but, I'd hate to see you or anyone else get hurt because you wern't able to stop



My $. 02 (you probably know what to do) fix it now. The cost of a master cylinder is cheap compared to down time, having it fixed mid run, towing bill etc. or worse a new rig.



O. K. I'll stop now - get those stoppers taken care of and happy (safe) trucking.