1999 WJ Limited 4.7L, 117k miles.
Problem: brake light comes on and stays on for miles at a time, then goes off and stays off in a similar fashion. Sometimes it comes on after you've started driving, sometimes it comes on when you turn the car on, sometimes it stays on until you turn the car off, sometimes it goes off on its own. Sometimes it goes through two on-off cycles in a single 10 mile trip. It will stay on for quite a while then vanish just as sneakily. I can't tie it to any one occurrence (going around a corner, braking, speed, etc.) as to when it comes on or goes off.
I did a search first and read the manual. Found where the red brake light can come on on account of a fluid fault (too low, fault at caliper) or e-brake sensor fault.
I cleaned the e-brake sensor/trigger and it seems to operate correctly--triggers the light when the e-brake is pulled up, makes it go off when you lower the e-brake.
I bled the brakes via the Hayes manual. No irregularities, there. I did find out that my right front CV joint boot busted and it made that area dirty (amazing I haven't felt it or heard it driving or turning). Other than that all for corners were relatively clean. Don't have a dragging brake or uneven wear. No mushiness or excessive travel in pedal feel.
The fluid level is pegged right in the middle of the reservoir on level ground.
What gives! It's acting like a short. Anyone had this problem?