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Well I know this beating a dead horse but I need to share..
My 76 has been in the shop( I work at a GM dealership) with various jobs this past week,The one I want to share is that I had all calipers,pads,rotors,hoses and MC last Summer.Very few miles on car since then. I was getting air in the system and decided to put another MC and brake valve, front lines etc.The brakes feel fine,stop fine but now the brake light is on. I looked at the fluid in the MC and the frt is clear but the rear is dark.Any ideas? Granted I can take it back to work and they will check it out again.Just curious at this point.
Well I know this beating a dead horse but I need to share..
My 76 has been in the shop( I work at a GM dealership) with various jobs this past week,The one I want to share is that I had all calipers,pads,rotors,hoses and MC last Summer.Very few miles on car since then. I was getting air in the system and decided to put another MC and brake valve, front lines etc.The brakes feel fine,stop fine but now the brake light is on. I looked at the fluid in the MC and the frt is clear but the rear is dark.Any ideas? Granted I can take it back to work and they will check it out again.Just curious at this point.
Danny
On an antique Roman Chariot methinks you can find some rust in the brake lines....so not too much imagination with that old DOT3 brake fluid, which is why DOT5 went into my car some decades ago.....
OH, and even after going 5, the stupid rear brake line still failed something about steel and mommy nature.....
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
The 'BRAKE" light performs two functions.
If you have a leak in the brake system the piston in the distribution block (brake valve) moves off center and turns the dash 'brake' light on.
When you pull up the parking brake handle, with the key ON, the same light will go on.
Disconnect the brown wire at the distribution block and with the key ON see in the light stays ON.
If it stays on then the problem is the parking brake switch needs to be adjusted.
If the light is OFF with the brown wire disconnected you can recenter the valve in the distribution block by applying pedal pressure and bleeding the front caliper or the rear caliper depending which way the valve is off center.
Well I know this beating a dead horse but I need to share..
My 76 has been in the shop( I work at a GM dealership) with various jobs this past week,The one I want to share is that I had all calipers,pads,rotors,hoses and MC last Summer.Very few miles on car since then. I was getting air in the system and decided to put another MC and brake valve, front lines etc.The brakes feel fine,stop fine but now the brake light is on. I looked at the fluid in the MC and the frt is clear but the rear is dark.Any ideas? Granted I can take it back to work and they will check it out again.Just curious at this point.
Danny
Danny, When did you first notice that the brake light was on?
You say you've looked in the master cylinder at the fluid. Are both reservoirs full or at least near the top and at equal levels? If they are not equal, you very likely have a leak in one side of the system, front or rear. Find the leak and fix it first. If the fluid levels are topped off and equal, move on to the next step.
Your brake light is telling you that there has been a pressure differential between the front and rear brake system at some point recently. The distribution block (just below your master cylinder) has a shuttle valve in it. If a leak develops on the front or rear system it will create a pressure differential, the shuttle valve will be pushed to one side or the other. This will push the plunger of the switch (sticking out of the center of the distribution block) and turn your brake light on.
It could mean that you have a leaking caliper in the front or rear of the car. It could also have occurred after you completed your brake job and bled the brakes. Since you say the brakes feel fine, I would examine each of the calipers to see if any of them have started leaking first. It is best to remove the wheels to do this to get a better view of the pistons. If you can find no evidence of leakage I would try bleeding the brakes again to see if there is any air in the system. This may also push the shuttle valve back into it's neutral position.
If the brake light stays on after doing all of this, you'll need to create a pressure differential to move the shuttle valve back to its neutral position.
Well folks the car is still in the shop.The tech is having a fit trying to get the light to go off.abled several times and still trying more scenarios on what to do next. We are a GM Dealer but no more old school guys around anymore.Its getting old to see my car on the lift for four days.Granted they are dealing with a come back cause it wasn't on before they worked o it besides I am good with the time but frustating to see no positive outcome yet.According to the tech I have good pedal and brakes.I will keep y'all posted.This time they discovered the power steering pump was leaking after I had all the hoses replaced,lol.One piece at a time.....
Well folks the car is still in the shop.The tech is having a fit trying to get the light to go off.abled several times and still trying more scenarios on what to do next. We are a GM Dealer but no more old school guys around anymore.Its getting old to see my car on the lift for four days.Granted they are dealing with a come back cause it wasn't on before they worked o it besides I am good with the time but frustating to see no positive outcome yet.According to the tech I have good pedal and brakes.I will keep y'all posted.This time they discovered the power steering pump was leaking after I had all the hoses replaced,lol.One piece at a time.....
Tell the tech to STOMP on the brake pedal several times and that'll turn the light off. Something I learned many years ago.
The 'BRAKE" light performs two functions.
If you have a leak in the brake system the piston in the distribution block (brake valve) moves off center and turns the dash 'brake' light on.
When you pull up the parking brake handle, with the key ON, the same light will go on.
Disconnect the brown wire at the distribution block and with the key ON see in the light stays ON.
If it stays on then the problem is the parking brake switch needs to be adjusted.
If the light is OFF with the brown wire disconnected you can recenter the valve in the distribution block by applying pedal pressure and bleeding the front caliper or the rear caliper depending which way the valve is off center.
To get rid of dark fluid bleed the brakes again.
Have you simply removed the brown wire from the brake pressure block to see if the brake lite remains on as Peter has recommended above?
And the hand brake off as well when testing.
Danny, When did you first notice that the brake light was on?
You say you've looked in the master cylinder at the fluid. Are both reservoirs full or at least near the top and at equal levels? If they are not equal, you very likely have a leak in one side of the system, front or rear. Find the leak and fix it first. If the fluid levels are topped off and equal, move on to the next step.
Your brake light is telling you that there has been a pressure differential between the front and rear brake system at some point recently. The distribution block (just below your master cylinder) has a shuttle valve in it. If a leak develops on the front or rear system it will create a pressure differential, the shuttle valve will be pushed to one side or the other. This will push the plunger of the switch (sticking out of the center of the distribution block) and turn your brake light on.
It could mean that you have a leaking caliper in the front or rear of the car. It could also have occurred after you completed your brake job and bled the brakes. Since you say the brakes feel fine, I would examine each of the calipers to see if any of them have started leaking first. It is best to remove the wheels to do this to get a better view of the pistons. If you can find no evidence of leakage I would try bleeding the brakes again to see if there is any air in the system. This may also push the shuttle valve back into it's neutral position.
If the brake light stays on after doing all of this, you'll need to create a pressure differential to move the shuttle valve back to its neutral position.
Good luck and let us know what happens... GUSTO
Hello Gusto....Just read the above and would like to know(for future reference) where exactly is the distribution block located and what does it look like???? Perhaps a pic would help if you'd be so inclined..I have a 78..........
mk's78 Mike
I went crazy trying to get the brake light off after a brake job. I purchased this tool and bled all of the calipers. The tool centers the piston while bleeding to equalize the pressure through the valve.Just take the switch out of the valve and replace it with the tool. then bleed the system. It worked like a champ and costs about $10.
Last edited by Street Rat; Apr 20, 2016 at 11:50 AM.
I have heard of this fix before. Give it a shot!
Yet another brake issue....
OH, and even after going 5, the stupid rear brake line still failed something about steel and mommy nature.....
trying to get the brake light off after a brake job. I purchased this tool and bled all of the calipers. The tool centers the piston while bleeding to equalize the pressure through the valve.Just take the switch out of the valve and replace it with the tool. then bleed the system. It worked like a champ and costs about $10.
