Brake light still on

[ztim]

I did some brake work and can't get the light to go off. I bled the brakes but am now worried I didn't do it enough. The brakes work just fine but it still drives me nuts. I need it to be safe.

[mp71conv]

Did you check the connection at the proportion valve?

[ztim]

I don't know what that is. If you can tell me, I willl check. Thanks

[Oldsmaniac]

You must determine if the front or rear brakes were the cause of the light coming on. If it was the front then you must bleed the rears more to get the sensor back to center position.

[ztim]

Okay. Thanks. I'll give it a try and let you know.

[oldiesallgood]

try to check for some poor grounding system, check also the wirings. these are the most common reason why it won't work..

[joe_padavano]

Originally Posted by ztim

I did some brake work and can't get the light to go off. I bled the brakes but am now worried I didn't do it enough. The brakes work just fine but it still drives me nuts. I need it to be safe.

First, what type and year of Olds? Disc brake or drum on the front? I assume you're talking about the BRAKE light on the dash, correct?

If it is the dash light, first be sure you didn't accidentally touch the e-brake. The light will come on if the e-brake is not fully released (or if it's sticking or if the switch is cruddy). You can temporarily disconnect the brown wire from the switch on the e-brake pedal. If the light goes out, you've found the problem.

Assuming the e-brake switch isn't the cause, the other most likely cause is the differential pressure switch. All cars built since 1967 have separate front and back brake systems so that a leak in one doesn't cause a complete loss of braking. Follow the brake lines where they come out of the master cylinder down to the frame. There will be a brass or cast iron fitting where both lines go in and three other lines come out. If you have disc brakes, this is also the proportioning valve. There should be a single brown wire going to it as well.

Temporarily disconnect this wire. If the light goes off, this is the problem. (if not, you have a short someplace that's unrelated to the brakes). The differential pressure valve is a spool valve that is normally centered in the housing. If you loose pressure on one half of the brake system (which can happen when you bleed the brakes) the spool moves to one end of the housing, triggering the BRAKE light. Usually it comes back when you've finished bleeding, but it can get stuck due to crud in the valve. Which end of the car was the last one you bled? Crack a bleeder at the other end of the car while pressing on the brake pedal and the light should go out.

[ztim]

Thanks! I'll give it a try. The car is a 1984 Delta 88 Royale. The last brake I worked was the right rear.

[ztim]

I read in another forum that the proportion valve can be bypassed. Wouldn't that hurt the brakes? The fella said his brakes stopped overheating. My ABS seems to have stopped working because my front brakes locked up a few times. No big deal but when that happened I automatically thought of the ABS.

[joe_padavano]

Originally Posted by ztim

I read in another forum that the proportion valve can be bypassed. Wouldn't that hurt the brakes? The fella said his brakes stopped overheating. My ABS seems to have stopped working because my front brakes locked up a few times. No big deal but when that happened I automatically thought of the ABS.

Your ABS seems to have stopped working because you don't have ABS. It was not available on an 84 Delta.

The only way to bypass the proportioning valve is to disconnect the lines and reroute them. There is a pushbutton on the valve that temporarily disables the residual pressure valve while you bleed the brakes.

[ztim]

Ok thanks. I didn't know that there is button to press on the valve. As far as the ABS..no wonder it dosn't work!

[Jim's rare 80]

Hey Bob. Did the button work. That is what I was going to get into next, on the other thread. Let me know. Thanks, jim.

[ztim]

I can't seem to find the button unless it is on the very top. I'll see if there is anything I cane remove to get it out of the way. Thanks. I'll let you know. Plus I need to make this the only thread for this dilemma. I don't know how I got two going unless I answered to someone else's question. I'll have to go back and look.

[joe_padavano]

Originally Posted by ztim

I can't seem to find the button unless it is on the very top. I'll see if there is anything I cane remove to get it out of the way. Thanks. I'll let you know. Plus I need to make this the only thread for this dilemma. I don't know how I got two going unless I answered to someone else's question. I'll have to go back and look.

The button is on one end of the proportioning valve, covered by a rubber boot.

[ztim]

On top there is a white plastic ...bolt?...going into the valve and it has a wire coming out of the top. Around that plastic thing is a 1/2 inch black metal band that is free spinning but will not come off. I think it is to protect the plastic part. I tried to pry it with needle nose but it won't budge without braking. Now, on the bottom there is a bolt with a soft center that depresses very slightly. That is probably rubber but it doesn't seem like a switch. If it is a switch, how long does it have to be depressed? Held in?

[ztim]

By the way...the bolt with the soft rubber center is a hexhead. Will it come off without dripping fluid all over and require bleeding?

[joe_padavano]

Originally Posted by ztim

On top there is a white plastic ...bolt?...going into the valve and it has a wire coming out of the top. Around that plastic thing is a 1/2 inch black metal band that is free spinning but will not come off. I think it is to protect the plastic part. I tried to pry it with needle nose but it won't budge without braking. Now, on the bottom there is a bolt with a soft center that depresses very slightly. That is probably rubber but it doesn't seem like a switch. If it is a switch, how long does it have to be depressed? Held in?

The "bolt" with the wire is the differential pressure switch that is causing the light on your dashboard to stay on. Just for grins, disconnect this wire. If the light goes out, the problem is in the valve. If the light stays on, you have a short in the harness someplace.

The soft rubber item is the cover for the button. It does not move very far. That needs to be pressed in while bleeding the brakes.

[ztim]

How do I remove the wire? The metal band, around the plastic thing that the wire goes into, is covering the plastic thing. I can't see underneath it. I doesn't just pull out does it?

[J-(Chicago)]

Haha I have this same problem on my 85. The easiest solution is to come up with clever beats and lyrics to the tone of the beeping dash alarm. I'm thinking of releasing an album by the end of the year.

[ztim]

No alarm. Just dashboard light.

[J-(Chicago)]

My idiot light beeps at me (like when you leave the lights on and open the door) for a good minute every morning, and my problem is with the metering block. Sometimes It's impossible to bleed the rear driver's side brake.
I'm not sure if dash alarm for the brake light is a 1985 only thing but if you have no beep, It's probably just your ebrake wire, and if your ebrake works fine, I'd just cut the wire to it (in an easily spliceable spot) and see what happens. I'm pretty sure that the dash alarms go off for OIL/Choke and Temp on an 84 though, Trying to remember.... I demo derby'd mine when I was 19 yrs old.

[ztim]

It was the proportion valve. I disconnected the wire and the light went out.