ASB light and brake spongish brake pedal

[MBurke]

I posted this in the 911 sectioin, but got no response. I thought I would put it here where it may get some more exposure.



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.

 

[THerman]

Fluid levels staying normal?? I don't know off hand of any overpressure bypass on the brake system... but it could all be due to the ABS system. Bad wheel speed sensor, or something. If so it would be trying to overide you constantly. I haven't had the abs kick in long enough to tell if this would cause the pedal to act as it does... Any pulsing or buzzing feeling in the pedal?

 

[illflem]

If you're not losing fluid it sounds like you may have an internal leak in either the master cylinder or ABS unit.



You should have an ABS relay in the underhood power center, if you don't the warning light will never go off. If I'm not mistaken the A/C compressor relay is the same as the ABS, try using it in the ABS's place and see what happens.

 

[Joe Mc]

Mike - Pop back and see my $. 02 - don't be offended - just giving MHO