Brake warning light on after brake job??

[BigRed]

I'm a rookie to drum brakes. Seems like all the trucks I've owned have all had new rear brakes. However, my burb does not. So, I put new shoes, wheel cylinders, and spring kits on the rear today. I also had the drums turned.

Anyway, now my brake warning light is on. Is this probably just an adjustment problem? I tried to get the hubs on there snug using the adjustment piece at the bottom, but maybe not. I also bled the rears again to see if that was the problem, but that wasn't it.

That brings up another point, whats the procedure you guys use to bleed the brakes? I had someone pump the pedal several times and then he held the brakes to the floor and then I opened the valve until there was no more spitting. However, it seemed logical to me that fluid should still have been coming out as he was holding it to the floor until I closed the valve. However, it didn't.

Thanks!

[Mike76251]

Holding the brake to the floor and no fluid comes out?
Something's blocking it then.
Perhaps a collasped brake hose or two?
Too much crud in the system?

[BigRed]

Originally posted by Mike76251
Holding the brake to the floor and no fluid comes out?
Something's blocking it then.
Perhaps a collasped brake hose or two?
Too much crud in the system?

Well, if I pump it fluid comes out with each pump but once I stop and hold it to the floor it slowly stops.

[Mike76251]

Did the master cylinder go empty anytime you were doing this?

[BigRed]

Well, it did get really low. Not sure if it went empty or not. I did fill it back up.

[old Rusty C10]

when youre bleeding the brakes yes the flow will stop. What i do is start at the furthest wheel ( Back right) and have someone pump and then hold after four to five pumps then i loosen the bleeder. it will spit out and stop. then i tighten the bleeder. yell pump and the guy pumps the brakes again he pumps three or four times and holds it again ya loosen bleeder and the fluid will spurt out and stop. You then check the master to see how low it is and add as necessary. You know youre done bleeding brakes when #1 the pedal remains firm when you pump it after that and ya let go and when your ebleeding the brakes the frothy air laden fluid doesnt come out when you release the bleeder.

If you let the fluid out of the master youve got alot of bleeding starting with the master through the whole system
also if the rubber lines are old and cruddy you may have to replace them.
also did you get the adjusters adjusted properly so that the shoes are not having to travel too far to the drm that would make the lite come on tooif ya need further help let us know

[BigRed]

Originally posted by old Rusty C10

also did you get the adjusters adjusted properly so that the shoes are not having to travel too far to the drm that would make the lite come on tooif ya need further help let us know

I think the adjusters are my problem. I don't think I have the shoes out far enough. I'll monkey with that once I get the front brakes done tonight.

[ElGracho]

The brake warning light comes on when the shuttle valve in the proportioning block moves. It's there to prevent a total loss of brakes when either the front or rear system gets a leak. When you are bleeding brakes, it looks like a leak to the shuttle valve and it goes from it's normal mid position to one end or the other. This happened to me when I rebuilt the rear brakes on my 87 but while I was in reading about it, it shifted back on its own. Vigorously bleeding the front brakes might shift it back too.

[BigRed]

Originally posted by ElGracho
The brake warning light comes on when the shuttle valve in the proportioning block moves. It's there to prevent a total loss of brakes when either the front or rear system gets a leak. When you are bleeding brakes, it looks like a leak to the shuttle valve and it goes from it's normal mid position to one end or the other. This happened to me when I rebuilt the rear brakes on my 87 but while I was in reading about it, it shifted back on its own. Vigorously bleeding the front brakes might shift it back too.

Thanks Joe. Once I get the front-end brakes done, I'll try bleeding them and see if I can get the light to go out. If that doesn't work, I'll try adjusting the rear brakes again and see what happens.

[old Rusty C10]

dont over adjust the rears tho the way i usually do it is make em tight enough so there is a slight bit of resistance when you try to slide off the drums. now ifyour drums are old and havent ben resurfaces you may have a lip there which makes it harder to check .

[Blue Beard]

Some of those had a reset button that was used when the resivoir got low enough and new fluid was bleed thru the system....

[teamroper!]

72 gm service manual says
The combination valve, located near the master cylinder, must be held in the open position while bleeding. This can be accomplished by installint Tool J-23709 with the open slot under the mounting bolt and pushing in on the pin in the end of the valve.



I guess if you don't have this tool you could have a third person hold in the pin with a screwdriver or something. Hope this helps.

[jimfulco]

30+ years ago an old mechanic showed me an alternate way of adjusting drum brakes. Get the slot aligned with the star wheel, adjust the brakes out until you just barely can't turn the drum by hand, pump the pedal to center the shoes, then make sure you still can't turn the drum. Tighten more if necessary. Then stick something (thin screwdriver, ice pick, etc.) through the slot to hold the adjuster off the wheel, & adjust the wheel 3 to 6 notches looser as needed. The Chevy place I worked at back then used the "back up real fast & pump the pedal" method, but they had a big parking lot to do it in.

[crackajacka]

thats the ebrake light right? if its that, then the drums are self adjusting, back up and stomp the brakes the repeat a couple of times then stomp the ebrake then release and it should go off if it hasnt already thats how i get mine to go off

[BigRed]

Thanks guys! Actually, I resolved this problem by simply bleeding the front brakes after bleeding the rears. Guess that moves something in the proportioning valve back.