Originally Posted by Landseer

I thought there were a pair of switches on the master cylinder. Seems like they fail, at least on earlier cars. Maybe I'm having alzheimers, but it seemed like whenever I offered-up bulb controller solutions the victims dialed-in on master cylinder switches instead and solved it. But if you have a spare, that's the easy first attempt. Then, changing the pair of bulbs (might have degradation of one or the other tripping the warning, or corrosion in the fixture).

Again, I'm dealing with the earlier cars and don't want to lead you too far astray on the 87+.