does anyone know what the brake light on the dash means it comes on when the brake pedal decides it wants to go all the way to the floor like theres no p[ower brakes but it doesnt do it all the time

thanks
tony

 

Yeah if the brake light comes on like that it's either the E brake is on or there is a problem with your brake system could be shoes and pads or a wheel cylinder or master cylinder or power brake booster.It definitely needs to be checked

 

Did you check your brake fluid? Was it low? Did you find the leak?

 

the brake system is all brand new to the wheels and it just started acting up im going to check the brake pads and shoes tommarow when its not raining and daylight there is no leaks and the resivoir is full i read somewhere that it could be the rear breakshoes may need to be ajusted so im going to try that and see if it helps

thanks for your replies and if anyone else has an idea let me know

thanks
tony

 

If the pedal goes to the floor it's hydraulics. New means new, it doesn't mean good.

Is the booster new?

 

yes the booster is new i think it lost the vacume from the engines i found a sparkplug pugging one of the vacume lines so who knows im just gonna have to look over everything in this truck to find out whats wrong thanks for all your advice and keep it commin '

thanks
tony

 

My guess would be the master cylinder. If your pedal goes all the way to the floor its allowing fluid to slip by. (Assuming you have no leaks)

 

1st off check to make sure your emergency brake switch isn't the culprit.
Starting about 1968 they required all vehicles to have dual brakeing systems.
One for the front, one for the rear (hence the dual reserviors under the cap)
Should one loose fluid, the other will still stop the vehicle.
If you follow the lines leaving the master cylinder you will find they go directly into a gizmo called a proportioning valve. This valve serves 2 purposes. 1, it restricts a certain amount of flow to the rear brakes on lighter GVW vehicles to prevent rear brake lock-up under hard brakeing conditions:
2, it has a piston in between the 2 systems that senses a differential in between them (before the proportioning valve) should a line or slave cylinder leak.(there is no exchange of fluid between the two)
Should one of the systems leak, the pressure will be greater in the non-leaking side causing the piston to shift to the other side and ground the proportioning valve switch which in turn illuminates the brake light thus indicating a problem.
Once the brakes have been repaired, pushing hard on the pedal re-centers the piston and shuts off the light.
To check to see if this is the culprit, pull the wire off the valve. If it is the light will go out. This is just an electrical ground.
Now you have to fix your leak and re-center the valve.
Good luck
Steve G.

 

From the symptoms you are describing I say you have a bad master cylinder. The brake booster isn't connected to the proportioning valve or warning system on this truck so it shouldn't light the warning light even without any vaccume at all going to it.

Here is a little explanation on nhow the brake systems work on our trucks, and what can cause it to go wrong.

When your brake warning light comes on, the brake fluid from the brake porportioning valve is "out of balance" due to a loss of hydraulic pressure from somewhere. What happens is if your front brakes fail, due to a cut hose or a leak. More pressure from the master cylinder's rear brake resevoir causes the proportioning valve to slide over and shut off the fluid going to the front brakes, so all the fluid goes to the rear brakes, instead. This prevents more loss of brake fluid and then you can stop the truck safely without losing your entire brake system. When the proportioning valve is in either shut off position, it will activate your brake warning light. The symptoms of this is the warning light will stay on steadily, and your brakes will be in a severly weakened state.

What can also cause the proportioning valve to activate, start to shut off one side of your brake system, (either front or rear). is a pin hole in one of the diaphrams in the master cylinder itself. Fluid leaks back into the master cylinder, through the pinhole, causing a loss of pressure to the apropriate side of the porportioning valve and makes it activate. The symptoms of this are steadily loss of pedal pressure, the light comes on after a while. You let your foot off the brake pedal, the fluid flows back into the master cylinder, the pressure equalises again, the light goes off.

And yet a third reason for this could be normal wear on your brakes. The more the lining is worn off, the less fluid you have in the master cylinder resevoir. After a while the level in the master cylinder can become low, and would need to be topped off. If it becomes too low, it will cause uneven pressure, at the proportioning valve, etc, causing it to activate. Fill it up with fluid to fix this, and check the linings.

hope this all helps.

 

thanks guys ill definatly be checking that when the sun comes up

thanks
tony

 

was rereading my old post to and realized i never found out what the problem was on this. after i retightened the lug nuts on the passanger side front wheel and a couple of hard slams on the brakes it quit coming on and the brakes work great.



tony