why is the brake warning light on? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jon Scully · 03-02-2011, 10:34 PM

Hey guys,

I am just completed a rear brake rebuild and hose change on my 71 4x4 k5.......

And the brake light on the dash came on....I have bled the brakes, and I think I got all the air out....not sure? Anybody know why this light comes on?

Also--Why do the drums not have an ajustment hole in the bottom of them? I think I adjusted the brakes enough when i put the drum on-- and did the back up and stop a few times.....but I still feel like there is an issue -- ie- the light came on on the dash, and my e-brake is not very tight?

Any comments ar advice is very welcome!! This group is great!

jon

**jaros44sr** · 03-03-2011, 01:40 AM

did you lock the pin from moving on the master cylinder??

Torrey72 · 03-03-2011, 05:25 AM

The Brake warning light, lights up when the proportioning valve is detecting a problem. As you step on the pedal, fluid pressure in the front and back brake lines must be at a equal pressure. Or the light will come on. Your problem could be one or a number of things. Such as air in the lines, bad wheel cylinder/s, bad master cylinder. broken or leaky line. Or the pads are so far out of adjustment that some pads are making contact and some need to be adjusted so they make contact with the drum. When you push down on the pedal.

Sounds like your setup is loose. Just go back over everything. Pull your drums off and re-setup each wheel. Compress the cylinders ,by hand, with them all hooked up and adjust the pads by hand with the drums off. Slip the drums on when you just have enough space to just get the drum back on. Take your time to re-bleed the brakes and don't be shy about the amount of fluid you put through the lines.

Hope this helps?

Burt4x4 · 03-03-2011, 11:29 AM

WHen I had drums and put new shoes inum I would drive in reverse tapping the brakes...light pressure at first and as they tighten harder pressure..works like a champ, yes in REVERSE!

Jon Scully · 03-04-2011, 01:41 PM

Thanks for the info Guys;

A couple of updates
1) NO I did not know about having to lock down the prop valve before bleeding-- I suspect this is my problem.
2) I checked all lines, and do not apear to have any leaks.
3) My plan will now be to 'reset' the valve, hold it in with tie wrap, and re-bleed the brakes.

Now- Aquestion: How far in does the valve button go when I tie it down? Right now, I suspect it is in the 'out' position, with only front brakes receiveing preassure-- It sticks out of the Master cylinder about 1/2in (including the little rubber boot) SO-- To reset and bleed the brakes again should this 'button' be flush with the Master cyl? or should it be flush with the rubber grommet?

Hope these are not silly questions-- I have just never bled a system that required this to be done, now I know lol!!!

OH-- By the way-- despite this minor hiccup- My import, safety and insurance are finally complete-- and I am offically on the road!!!!! Just wish the snow, slush and salt would leave so I can start drivin all the time ( I took it out once in this weather and every little paint chip on the damn thing showed a new little cancer spot Blahhhhhh winter!!!!!)

**jaros44sr** · 03-04-2011, 04:23 PM

if you have the time, I will try to get a demension this weekend. Not sure if a tiewrap will grip enough of it. Apiece of sheetmetal, bent to a 90 degree, and drill holes to mount up to the mounting bolts of the unit

Jon Scully · 03-04-2011, 04:41 PM

I do have the time-- and that would be greatly appreciated!

**jaros44sr** · 03-06-2011, 10:51 AM

seems like the pin sticks out about 1/4-5/16"

took the rubber boot off for clarity, the pin that has to be centralized is under the white plastic fitting w/ black boot

RustyParts · 03-07-2011, 11:19 AM

Of course GM had a tool. You may get some idea how it works from the pic and create your own. Good Luck

**jaros44sr** · 03-07-2011, 04:38 PM

Quote:

Originally Posted by RustyParts

Of course GM had a tool. You may get some idea how it works from the pic and create your own. Good Luck

didn't know that tool existed...thanks for the info., and pic.

what's up with the jimmy??

RustyParts · 03-10-2011, 12:49 PM

Quote:

Originally Posted by jaros44sr

didn't know that tool existed...thanks for the info., and pic.

what's up with the jimmy??

Not Much, can't seem to stretch the social security check far enough.

Jon Scully · 03-22-2011, 02:13 PM

Well A Couple of thank you's are in order!

To- Jaro-- Thanks for the info-- The prop valve was the issue!

To Rusty-- Thanks for the PIC-- I fabbed up a small tool to hold the valve down-- clamps etc were not effective-- and the tool worked great-- Looks nothing like the GM tool you pictured-- But mine gotthe job done!

Once the valve was set on there, and I acquired an assistant (at the rate of 2beers per hour), we had it complete and working great!

Thanks Again for all the assistance!
Jon

03-02-2011, 10:34 PM	#1
Jon Scully Registered User Join Date: Jan 2011 Location: Thunder Bay Ontario Posts: 97	why is the brake warning light on? Hey guys, I am just completed a rear brake rebuild and hose change on my 71 4x4 k5....... And the brake light on the dash came on....I have bled the brakes, and I think I got all the air out....not sure? Anybody know why this light comes on? Also--Why do the drums not have an ajustment hole in the bottom of them? I think I adjusted the brakes enough when i put the drum on-- and did the back up and stop a few times.....but I still feel like there is an issue -- ie- the light came on on the dash, and my e-brake is not very tight? Any comments ar advice is very welcome!! This group is great! jon

03-03-2011, 01:40 AM	#2
jaros44sr Senior Member Join Date: May 2006 Location: Philadelphia, Pa. 19454 Posts: 9,759	Re: why is the brake warning light on? did you lock the pin from moving on the master cylinder?? __________________ Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim

03-03-2011, 05:25 AM	#3
Torrey72 Rollin in my K5 toaster Join Date: Oct 2010 Location: Pacific Northwest Posts: 254	Re: why is the brake warning light on? The Brake warning light, lights up when the proportioning valve is detecting a problem. As you step on the pedal, fluid pressure in the front and back brake lines must be at a equal pressure. Or the light will come on. Your problem could be one or a number of things. Such as air in the lines, bad wheel cylinder/s, bad master cylinder. broken or leaky line. Or the pads are so far out of adjustment that some pads are making contact and some need to be adjusted so they make contact with the drum. When you push down on the pedal. Sounds like your setup is loose. Just go back over everything. Pull your drums off and re-setup each wheel. Compress the cylinders ,by hand, with them all hooked up and adjust the pads by hand with the drums off. Slip the drums on when you just have enough space to just get the drum back on. Take your time to re-bleed the brakes and don't be shy about the amount of fluid you put through the lines. Hope this helps?

03-03-2011, 11:29 AM	#4
Burt4x4 Registered User Join Date: Feb 2000 Location: Modesto, CA Posts: 1,842	Re: why is the brake warning light on? WHen I had drums and put new shoes inum I would drive in reverse tapping the brakes...light pressure at first and as they tighten harder pressure..works like a champ, yes in REVERSE! __________________ 1972 K5 MPFI454/Sm465/Np205/D60/14FFd/Re-Centerd H1s w/Swamper Iroks

03-04-2011, 01:41 PM	#5
Jon Scully Registered User Join Date: Jan 2011 Location: Thunder Bay Ontario Posts: 97	Re: why is the brake warning light on? Thanks for the info Guys; A couple of updates 1) NO I did not know about having to lock down the prop valve before bleeding-- I suspect this is my problem. 2) I checked all lines, and do not apear to have any leaks. 3) My plan will now be to 'reset' the valve, hold it in with tie wrap, and re-bleed the brakes. Now- Aquestion: How far in does the valve button go when I tie it down? Right now, I suspect it is in the 'out' position, with only front brakes receiveing preassure-- It sticks out of the Master cylinder about 1/2in (including the little rubber boot) SO-- To reset and bleed the brakes again should this 'button' be flush with the Master cyl? or should it be flush with the rubber grommet? Hope these are not silly questions-- I have just never bled a system that required this to be done, now I know lol!!! OH-- By the way-- despite this minor hiccup- My import, safety and insurance are finally complete-- and I am offically on the road!!!!! Just wish the snow, slush and salt would leave so I can start drivin all the time ( I took it out once in this weather and every little paint chip on the damn thing showed a new little cancer spot Blahhhhhh winter!!!!!)

03-04-2011, 04:23 PM	#6
jaros44sr Senior Member Join Date: May 2006 Location: Philadelphia, Pa. 19454 Posts: 9,759	Re: why is the brake warning light on? if you have the time, I will try to get a demension this weekend. Not sure if a tiewrap will grip enough of it. Apiece of sheetmetal, bent to a 90 degree, and drill holes to mount up to the mounting bolts of the unit __________________ Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim

03-04-2011, 04:41 PM	#7
Jon Scully Registered User Join Date: Jan 2011 Location: Thunder Bay Ontario Posts: 97	Re: why is the brake warning light on? I do have the time-- and that would be greatly appreciated!

03-06-2011, 10:51 AM	#8
jaros44sr Senior Member Join Date: May 2006 Location: Philadelphia, Pa. 19454 Posts: 9,759	Re: why is the brake warning light on? seems like the pin sticks out about 1/4-5/16" took the rubber boot off for clarity, the pin that has to be centralized is under the white plastic fitting w/ black boot __________________ Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim Last edited by jaros44sr; 03-06-2011 at 10:54 AM.

03-07-2011, 11:19 AM	#9
RustyParts Registered User Join Date: May 2006 Location: Wyman, Kentucky Posts: 403	Re: why is the brake warning light on? Of course GM had a tool. You may get some idea how it works from the pic and create your own. Good Luck Attached Images __________________ 1972 GMC Jimmy, 4WD, 454 CI, 350 Turbo, 4" lift, 35" tires The math teacher said my son "Bubba" could be a mathmatical genius. cause he's got 13 fingers!

03-22-2011, 02:13 PM	#12
Jon Scully Registered User Join Date: Jan 2011 Location: Thunder Bay Ontario Posts: 97	Re: why is the brake warning light on? Well A Couple of thank you's are in order! To- Jaro-- Thanks for the info-- The prop valve was the issue! To Rusty-- Thanks for the PIC-- I fabbed up a small tool to hold the valve down-- clamps etc were not effective-- and the tool worked great-- Looks nothing like the GM tool you pictured-- But mine gotthe job done! Once the valve was set on there, and I acquired an assistant (at the rate of 2beers per hour), we had it complete and working great! Thanks Again for all the assistance! Jon



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