I believe the break lights are switched on by the break pedal arm being pushed away from a switch under the dash & has nothing to do with bleeding your breaks. If you have a solid pedal with no leak down your system is fine...might be a bad switch...look under the dash and up on top of the break pedal...you'll see it...after 36 years sometimes they go bad. Good luck

Alan

The brake light comes on when the proportioning valve has been tripped to one side or the other. It means there is more pressure on one side. You either have air in the system, or a leak(internal) in the master cylinder, or there is not enough fluid in the mast. cyl. to completely apply the brakes.
Check the fluid level in the mast. cyl. If it's low enough that you can see the bottom, you have a leak somewhere in the system. If it's full, and you have a spongy pedal, then there's air in the system, or the mast. cyl. is leaking internally.
I would reccommend bleeding it if the mast. cyl. is full, first. If that doesn't solve the problem, then you probably need to o/haul the mast.
The brakes on these cars are bad about sucking air into the system if there is any runout in the rotors. If you bleed it, and it's ok 'till you drive it for awhile, and then it gets spongy again, then you have excessive rotor runout, and will need the rotors resurfaced.

From what I have read here when Ken writes on this subject, I would say that Joel is right on target.

Yep, right on target.  And they can be difficult to bleed.

But........doesn't everyone have a pressure bleeder?!
Best $300 bucks I've spent in years!