Brake Warning Light

**tgarison** · 04-01-2011

Hey all,

I recently bought a '99 Pontiac Grand Prix GT with 177,1XX miles and one of the problems its had ever since i got it is the brake warning light comes on as soon as you turn on the key and wont shut off unless you turn off the key. The fluid level is good and the brake pressure is good, even with the parking brake fully disengaged the light stays on. I'm thinking it might be the parking brake sensor do any of you have any ideas on what could be causing this?

Thanks,
tgarison

**matt5112** · 04-01-2011

Is it the red light?

**tgarison** · 04-01-2011

yeah the red brake warning light in the dash, the abs light comes on occasionally but thats cause the the wheel bearing and the vehicle speed sensor is getting old and i am planning on replacing that whole assembly.

**matt5112** · 04-01-2011

is it just the brake one? the E brake one doesnt come on as well?

**tgarison** · 04-01-2011

just the red brake warning light i have never even seen a dedicated light for the E brake, and i dont know if this matters but all the brake lights seems to be working.

**dsmuts** · 04-02-2011

Just unplug one sensor at a time and if the light goes out you'll know what sensor is bad.

**tgarison** · 08-30-2011

Hey all,

This is just an update on this thread I was driving my GPGT to a wrecking yard the other day on the edge of town to look for some parts and I was going about 70MPH I finally saw the wrecking yard and hit the brakes pretty hard to slow down when i hit the brake it felt like the brakes weren't there at all! I am wondering if perhaps the brake pads being worn out could somehow trip the sensor for that light? I am trying to get my car ready for a bit of a road trip and will trying replacing the pads and rotors next time i get paid. I know this is a stupid thing to post but its the only thing i can think of that could cause this. What do you all think?

Thanks in advance,
tgarison

**dsmuts** · 08-30-2011

is the fluid full?

**Hippo Machine** · 08-30-2011

The brake warning light come on for 1 of two things.

1. You have the e brake engaged.
OR
2. The sensor has noticed a drop in pressure in the system.

If you braked and they didn't work correctly, you are definitely losing pressure somewhere, meaning you are loosing brake fluid.

I suggest checking to make sure there is enough fluid in the reservoir under the hood. If it is between the min and max lines and there is enough fluid, then I'm not sure. But if there ISN'T enough fluid i would say have someone watch the under side of your car while you pump the brake pedal to see if any fluid comes out.

If fluid comes out that means you got a leak obviously and have to fix it or get it fixed.

The brake light does NOT come on for brake pads, the brakes have a built in thing that screeches when you have low brake pads.

Hope this helps.

**dsmuts** · 08-30-2011

brake light also comes on when your low on fluid

**Hippo Machine** · 08-30-2011

Yes, I said that. It comes on when pressure is low in the system, meaning it is losing fluid somewhere.

**dsmuts** · 08-30-2011

if your brakes are really wore down and the piston is pushed pretty far out the fluid will be low enough for the brake light to come on without a leak

**Hippo Machine** · 08-30-2011

Originally Posted by dsmuts

if your brakes are really wore down and the piston is pushed pretty far out the fluid will be low enough for the brake light to come on without a leak

Doubt it.

**Scottydoggs** · 08-30-2011

check your pads for wear, and look at the top of the parking brake lever for the plunger/sensor, it may be sticking or dead, thus keeping your brake light on, my regals used to stick and stay on.

**dsmuts** · 08-30-2011

Originally Posted by Hippo Machine

Doubt it.

I've seen it many times

**Hippo Machine** · 08-30-2011

Originally Posted by scottydoggs

check your pads for wear, and look at the top of the parking brake lever for the plunger/sensor, it may be sticking or dead, thus keeping your brake light on, my regals used to stick and stay on.

He said it felt like he was braking when he pressed the brake, so it wouldn't be the e brake. Pads wouldn't set off the light.

**Scottydoggs** · 08-30-2011

as your pads wear the fluid drops, but the op says the fluid is full. and a mushy pedal would make the brake light come on too, could be bad master cylinder or air in the lines, but op says he has a firm pedal.... then says the brakes seemed to fade i guess under "HBS" aka "heavy braking situation" so check for pad wear, unless the pedal hit the floor. then air in the lines or master cylinder.

**1LoudGrandPrix** · 08-31-2011

Originally Posted by dsmuts

I've seen it many times

has done it twice to me!

**tgarison** · 09-06-2011

Hey guys,

I hope this will be the last update on this thread I think i found out what was turning that light on i traced the parking brake (e-brake) up to where the sensor is and found the single wire coming off of it with the key turned on i disconnected the wire from the sensor and the light instantly shut off. Just to be sure i reconnected the wire and the light came back on. So I just disconnected the wire and left it hanging.

Thank you for all your help!
tgarison

**Iceman6669** · 09-07-2011

Originally Posted by Hippo Machine

Doubt it.

Dont doubt it Hippo.. It happened to me....Brake light came on.. Checked everything and nothing fixed it, so i decided to do a brake job, and wala.... Fixed it.