9--your description is the classic case for mismatched bulbs in the brake lighting system. The bulbs have to be perfectly balanced for resistance, as someone posted earlier, and if you insert two bulbs from two different manufacturers the chances are excellent they won't have exactly the same resistance, even though new, and the light will come on. This also holds sometimes when you replace a burned out one with the same brand. The newer bulb takes more/less wattage than the one that isn't burned, and this will cause the bulb warning light on the dash to light. If the problem goes away after he has stepped on the brake a couple of times it's because the bulb elements have warmed up and are closer in resistance. And if he waits a few minutes, the elements cool off, there is more/less resistance in one than the other, and the warning light will come on. If he has replaced the lights three times and after a period of time the bulb warning light comes on whenever he steps on the brake and no bulbs are burned, I would look closely at the sockets and see if there is a bad wiring connection, whether the base contact is too flattened or damaged or there is some corrorsion on the contact points inside--all of which would cause more resistance and unbalance the system. Dick