My brake light is on... the pedal is low ;( but they seem 100% functional...
any hindts?
I'll check fluid level asap.

Could be a leak somewhere in the system or it could be a weak master cylinder. If your fluid level is low...a leak. If the fluid level is normal...master cylinder.

Ready for this one???   Bare with me because this one is tricky.

Up to 1975 the light goes on and off as you lose pressure or get it back.

OK on 1975 and up Corvettes, once you have a brake fault (proportioning valve sees low pressure) the only way to get the light to go back off is to apply very high  pressure to it. Once it is lit, it is lit until you fix the problem that will increase the pressure. Once the valve sees high pressure it will go off itself. Their way to make sure you repair the brake system.

Try pumping it several times to pump it up and see if it gives you enough pressure to turn it  off, or....... fix your brakes.

cj5nutz38945.5452662037

Is your e-brake pulled up a notch or two?
If not, then the above suggestions would be right on.

[QUOTE=Adams' Apple]Is your e-brake pulled up a notch or two?
If not, then the above suggestions would be right on. [/QUOTE]

 

Thats tooo easy Joel  

Check everything else first.

Could be a leak in your break line/lines.  I'ld check that out too.

My pvc valve it ratling like a can of marbles.
I've never had that happen before so I was quite upset when I heared that "clinky" sound from my engine bay.....
Is that a possible cause?
I haven't driven that car for a few days so I've not looked into the issue more...

On my 78 the brake lite came on this past spring, and the brakes got real
mushy. First thing I did was check the brake fluid level an it was right up
to level and fine. So I replaced the master cylinder and the brakes
returned to normal for about 50 miles then did the same thing again. As
everyone knows, we can never trust rebuilt masters, so I replaced it again
with a brand new unit with the same results. Eache time the fluid level
would remain at level. The brakes were bleed properly each time as well
as the master cylinder being bench bled prior to installation. However,
each time I bled the brakes I got air out of one of the rear calipers. So I
thought bearing are going bad causing the calipers to suck in air.
Checked the bearing with a dial indicator and for any issues and didn't
find anything wrong. However, each time I bled the brakes I got air. I
then just replaced the calipers from the originals to the new stainless
steel type and the problem has since been gone.

The moral of the story is that even though your brake level is a good
indicator of what part of the system is faulty, calipers leaking or master
cylinder leaking internally. This rule is not always the case. In my case
the calipers were not leaking fluid out, but sucking in air each time I used
the brakes.

[QUOTE=ammo6]On my 78 the brake lite came on this past spring, and the brakes got real
mushy. First thing I did was check the brake fluid level an it was right up
to level and fine. So I replaced the master cylinder and the brakes
returned to normal for about 50 miles then did the same thing again. As
everyone knows, we can never trust rebuilt masters, so I replaced it again
with a brand new unit with the same results. Eache time the fluid level
would remain at level. The brakes were bleed properly each time as well
as the master cylinder being bench bled prior to installation. However,
each time I bled the brakes I got air out of one of the rear calipers. So I
thought bearing are going bad causing the calipers to suck in air.
Checked the bearing with a dial indicator and for any issues and didn't
find anything wrong. However, each time I bled the brakes I got air. I
then just replaced the calipers from the originals to the new stainless
steel type and the problem has since been gone.

The moral of the story is that even though your brake level is a good
indicator of what part of the system is faulty, calipers leaking or master
cylinder leaking internally. This rule is not always the case. In my case
the calipers were not leaking fluid out, but sucking in air each time I used
the brakes. [/QUOTE]

I know your going to think im nuts..  but if you have a parking lot nearby..  this works well..  block off a caliper and then brake a bunch of times when the lot is empty (definitely not safe to drive ont he streets)... if it stays firm with the right rear blocked off at rear distribution then you know it is the right rear...

it can be a pain if your brake lines have "bonded" with the proportioning valve...  but when I get real frustrated I'll block off the rear brakes..  and see how it does..  one brass plug cuts the problem in half.

 

Could it also be a bad proportional valve?
Runout in the rotors will cause the air problem. Gotta have less than .005" TIR.