BRAKE ALARM, BRAKE FAULT

First, Have your Battery tested. The Alarm systems in Ford made Products are very sensitive to Voltage. There are 3 systems in the car which interrupt power, the Alarm system (horn honking) and the Battery saver and finally the starter interlock system.

The Alarm system will do several things to disable the car from starting. It will reduce the voltage to the starter to prevent the engine from turning over. Some will even kill the ignition system so that if the starter is jumped, the car still won't start.

The Battery saver will disconnect any system to prevent discharge below a minimum threshold. Unfortunately, when the Alternator is working extra hard to charge a really bad battery: it will disconnect the charging circuit because it reads the Draw going to the Alternator to produce the power as a parasitic drain. Even at 70mph I have seen the charging disconnected and the vehicle coast to a stop when the electric runs out.

The last system worth mentioning is the Starter interlock. Under the dash and at the top of the Brake pedal lever is a switch. When you press the brake pedal, the switch allows the starter to crank provided the shifter is not in D or R. Drivers feet routinely hit this switch and either move it or break it. When it breaks it can short and drain the battery.

As you mentioned a Random problem, the Brake switch can shake to create a random problem if it is loose or broken. Your rear brake lights can be affected.

With the horn honking, at least part of your problem is the Alarm system. You can have a bad ignition switch too, which reads the keychip to disable the alarm. Your keychip may be bad and setting off the Alarm.

I had a new Lincoln myself which set off the Alarm randomly. I actually slept inside the car one night so I could turn off the alarm in the Apartment complex parking lot. Did'nt know if it would start again if the battery was disconnected and then reconnected. The Battery was shorted with less than 1000 miles on the car. It was a factory defective battery less than 3 months old.

But your car has many years and miles on it so it was worth mentioning the wear items. I hope my solution is helpful.

Low on brake fluid? worn brakes?

check your vaccum booster diaphram

Check your brake fluid level as this would bring this light on the dash if its low

it sounds like you may have a Bad Brake Master Cylinder and it is Sending the Code to the Computer Causing the Light. How does the Pedal Feel When Pressed???? Please rate my Response, I need all the Help that I can Get! Thanks!

due to icy temperature the your brake fluid froze i suggest that you might flash the brake fluid..every 2 yrs the two thumbs up to flash your brake fluid because when it get old due the boiling point went low that can cause or losing brake in high or low temp..let me know what happen after flashing your old brake fluid

Try carefully topping up the brake fluid, this can happen when the level falls as the pads wear down especially when cornering

it is probably a problem with the alarm system you could try pulling the fuse for it

inset the key and switch on to position 2
Scroll through the warning display untill you get the service indicator apears
Press and hold the reset button on the left of the dash apnel for about 4 mins
You will be asked if you want to reset
Press anh hold the reset button again until you hear an audible warning
It should now show the new interval to a service