Dennis;

...sounds like the "Brake Warning Indicator" which combines handbrake off rest position AND dual hydraulic brake system imbalance indications...to verify which on of those systems is activating the light, (With IGN ON) pull wires, on at a time, from Brake Failure sensor block, and Handrake lever...they both supply a ground, so either one can complete current path and cause Indicator to light up. Once you know which switch is causing lit indicator, next course of action should become clear.

Good Hunting