since you bled the brakes, your pedal traveled further than usual.. and i've ran into that problem with the 76, sometimes the bias (proportion) valve sometimes sticks a little, causing the pedal to travel further and light to come on(unless the switch on the parking brake is stuck...) .  I've gotten it to go off by sharply hitting the brake pedal... sometimes the valve sticks a little, and a good sharp pump or two brings it back.  From what i know, the proportion valve is suppose to block off the front or rear brakes should a loss of pressure happens to that end, allowing some braking to the "good" end...    otherwise, the parking brake switch is stuck, its under the cover with the parking brake lever,  should be a switch off to the side of the lever much like a door light switch...