the brakes were not fixed properly some part is installed wrong
It would be against the law for a motor manufacturer to fit a light which could cause the brakes to fail.
only if it doesnt have fluid.
Keypad is battery operated on all Ford,Lincoln and Mercury vehicles.Batteries are NOT easily replaced.These units self destruct when opened.New units are available for about 75.00.
you have brake fluid leak in your brake system somewhere that need to be check.
It would either be a bad wire in the circuit from the brake light switch on the brake pedal to the bulbs, OR the bulbs have 2 filaments in them and the one that comes on when you apply the brakes are worn out, OR someone put the wrong bulbs in(single filament). I would change the 2 bulbs first.
On a 1991 Lincoln Continental : I'm not a mechanic / technician but I have never heard of aluminum heads for the 3.8 litre Ford V6 engine So , I would assume they are cast iron
Would have been built for R12, can be converted to R134a.
You might need freon
No, as being a master mechanic, it would have nothing to do with it.
Did you check the vacuum hose or did you refill the brake fluid?
It isprobably not getting fuel or not getting spark.