hey anyone know why the brake light on my dash stays on? welli saw that i was low on fluid. so i added more but the light went off for a couple of minutes and then when i came to a stop, the brake light came back on. im not sure what would cause that to happen. My brake pedal does feel spongy. and it seems to go down farther to the floor then usual. any help would be appreciated. thanks

 

Sounds like you have a brake fluid leak. This would cause the level to drain down while you are using the brakes. You could also just have air in the lines, but it shouldn't cause the light unless its working its way back to the master cylinder (almost never happens).

First thing I would check would be the calipers and wheel cylinders. Check the bleeder valves and make sure that they are snug, but not overly tight. While you do this, you could also bleed the brakes. If you have someone to help you, to bleed the brakes, make sure the master cylinder is full and the cap is on. Get the appropriate wrench (10mm IIRC) for the bleeders, and start bleeding from the passenger side rear. The second person will pump up the pedal until it feels nice and firm, then push down while you open the bleeder. You may want a clear section of tubing to put over the end of the bleeder to direct the fluid into a jar or bucket to minimize the mess. While the bleeder is open, the person inside must keep the pedal on the floor until you have closed the bleeder, then start over again. After a few pumps, you should check the level in the master cylinder and refill as necessary. Keep doing this on the passenger rear until you get nice clean fluid out. Repeat on the drivers rear, passenger front, and drivers front in that order until nice clear fluid is at all 4 wheels. ALWAYS check the master cylinder level after every few pumps. If you suck air into the master cylinder by running it dry, you'll not only have to start over again, but you really would need to pull the master cylinder off and bench bleed it, then do everything all over again until you for sure got all of the air out of the lines.

I suspect that, since you had to add fluid, you have a leak somewhere in the system. If after inspecting all 4 corners you don't find the leak, inspect all of the brake lines all the way back to the master cylinder.

Good luck.

BTW, I'm moving this into General Tech Help to get more attention.

 

Look for a wheel with some fluid buildup on the outside or inside first. This will send you in the right direction in most cases. IF you do find a tire or wheel with brake fluid all over it, be sure to fix the problem and then replace the brake pads or shoes on the same axle also. It's almost inevitable that a leak will get brake fluid over everything and ruin the stopping ability of the pad on that axle. It's best to keep that axle matched up the same, by doing both sides. Strange braking can result from just fixing one side. Normally dangerous.

Its more common for the rear to have a leaky wheel cylinder if you have drum brakes. Discs hold up better normally, but you'll have to look. The spongieness you describe makes me think its the back, but look.

If you use your vehicle off-road, you might take a carefull look at the hose feeding the rear axle. Some of us have raised or even lowerred our vehicles and caused this hose to become stretched or rubbing the wrong way also. I've even seen this problem on front axle hoses, but most of the time folks see those and think about them.

Another common problem is simple age of fluid and contamination from moisture. This is actually more prevalent the more the cap is opened, but will happen even when sealed the whole time because of age. The master cyclinder may act up due to this contamination and start working again with fresh fluid. Once a year I do a very simple thing to all 5 of our Chevies. I simply remove a certain amount of fluid without causing air to come into the sytem and replace it with new fluid. IF I feel the master was contaminated I will change it and the fluid in the WHOLE system. A contaminated system is easy enough to sort out. The first hint is that there are no leaks, and you have trouble with it anyway. The second is that when you open it up and its still full of fluid, but it's about the ugliest fluid you have ever seen, cloudy, rustty etc.

Yes, lines do give out from time to time, also. I have one that has corrosion on the outside of the rear main line and it's not allowed on the road till the whole line is replaced. Doesnt leak, YET.

Anti lock brakes have some other features better serviced by experts and not by advice found on forums.

BTW this is written for all readers, I didnt look to see what model you have.

Sp errors.

 

Just for my information, how do I plainly REPLY to the post in general? I had no intention of replying to the second post, but only the original. What am I doing to cause the note on the right bottom?

 

Wow, finally someone on here that is as particular as me about preventative maintenance. I too drain older brake fluid from the res. about once a year in my older vehicles. If you have 4 wheel disks, it is also a good idea to suck out some fluid from the calipers as these are the lowest point in the system and where all trash collects. I use a brake evacuation device (fancy term for brake sucker) to actually pull the fluid out of the calipers making 1 person bleeding VERY easy.

Since we're talking about brakes here, another thing to note, when you change out pads on a disk setup with ABS present, you should not just force the piston on the caliper back in without having the bleeder open. You do not want to force all of the garbage that collects in the caliper back up through the ABS pump. Bad things can happen and the ABS pump is not cheap.

To reply directly to a specific post, you must click on the reply button on the top of the post you are replying to.

 

ok guys well i just found out why the brake light was on. it was the master cylinder that went bad