On the dash of my wifes 1989 Crown Victoria, there is on the left side of the instrument panel a good size bright "Emergency Brake" warning light.... which is supposed to light up only when the emergency brake is engaged.

This light is lit constantly with the emergency brank pedal in the full "Brake Off" setting and has been that way for some time. I assume the problem is a failed sensor or switch but my knowledge of the circuit is zilch.

I have tried to locate a switch or sensor to no avail. The thought occurred to me lately that perhaps the light also comes on should there be a problem in the brakes elsewhere. The brakes seem to function properly but the thought lingers.

I await your reply. (Joe)

 

From what I can recall, there were 3 reasons that could cause that lite to come on.
The first of course was , the switch at the parking brake mechanism.
The second was a low brake fluid level in the master cylinder.
The third was a switch in the brake hydraulic system (proportioning valve) that would cause the lite to come on if there was a loss of pressure in one of the brake lines to the wheels.
If a careful check under the vehicle revealed no leaks of any kind, then you might check the fluid level in the master cylinder.
The last check would be to check the parking brake switch at the parking brake pedal assy. To confirm that, all you had to do was to remove one of the wires to the switch and if the lite went out, the switch was defective.
There was a magnetic sensor under the master cylinder on some vehicles that when the fluid level got low enough the magnet would close the sensor contacts and cause the red brake lite to come on. That red warning lite is supposed to warn you, to determine why the lite came on and driving it that way could be asking for possible brake system failure.

 

The brake fluid within the master cylinder is right up to the proper level mark.

There are no brake fluid leaks anywhere.

I've tried to find that parking brake switch so that I could remove one of the wires but for some reason cannot locate it.

My wife, may she rest in peace, had a heavy foot with the break pedal.... never let the car slow down normally for a upcoming stop sign, red light, whatever... it was always foot on the gas pedal until about 50 feet from the stop area, then heat up the brake pads and hold on. The weird thought passed thu my mind... would metal shoe to metal drum have some sensing device that could cause this light problem?

Any idea where that emergency brake switch might be?

 

If you can , you may need to kneel down and look under the dash in the area where the parking brake pedal is located. When the pedal is released it usually comes back to it's stop and also contacts the parking brake switch. Work the pedal with your hand and watch where it stops. There should be a small switch with 2 wires on it.

 

Hanky.... Sorry to be so long in getting back. I had some other work to do on that crown victoria so after I took care of the other work, I finally managed to get under the dash, took off the fancy covering/moulding etc and found that brake switch.

I removed the hot wire leading to it BUT the brake light still stays on when the key is on. Apparently it's getting voltage from some other source... next step is to remove the bulb if I can get access to it.

 

Before you do that , look at the bottom of the master cyl and if you see 3 wires going to that area try unplugging the plug from the brake fluid level sensor. If the lite goes out the sensor is defective. I know the lite is annoying,but it's there for a reason. And to consider removing the bulb,,,,,, well you know what I'm driving at !

 

Yes, understood... removing the bulb is not a good idea. I'll check that master cylinder connection/plug in the morning and will get back to you.

 

Hanky... Removing that electrical plug from the master cylinder caused the light to go out. However..............

You're very first reply back in April of 2013 contained three causes of my problem, the cause of this dash brake light was indeed a master cylinder low fluid level. Back then I had assumed, judging by the fluid level outline on that semi clear reservoir that it was right up to the "max" mark. Being a mechanic in the marine line for many years, I should know better than to assume anything.

Today, looking closely at that line and rocking the car... the line didn't move. Removing the cap from the reservoir revealed that the fluid line being right on the "max" mark was simply a faded marking on that white reservoir where the fluid had been for many years. In removing the reservoir cap, the fluid was visible but not up to the "max" mark. Adding fluid to bring the level up to that mark.... the brake light on the dash went out.

I feel like such an idiot not following your instructions to the letter as posted in the #2 post above... my humble apologies. Apparently my mind was so locked into that brake light switch near the emergency brake pedal, it became blind to any other possibility.

In thinking back quite a few years, my wife had a brake job done at some local shop, linings, pads, a couple drums. It was shortly after that job that the brake light would come on intermitently, then in recent years, on constantly. Possibly they neglected to refill the master cylinder as there was never a brake hydraulic leak back then, and in checking today... still leak free.

So again Hanky, my apologies for not paying full attention to the cures in your reply of 04/06/2013, it won't happen again.

Some one once said: "To late we get smart and too soon old."... I get the feeling they may have been talking about me.

 

Sometimes we get lucky and this time we both got lucky !

I'm afraid you may have to take a way down place in the older dummer department because my pop used to always say , son it seems the older you get the dummer you're getting and I've managed to keep 1st place for quite a while now !