This sounds like the case. When you flip the test lever, the light will come on, and not go out again until you do the following. First, flip the switch back to the original posistion. Second, remove the battery cable. ( either one) for about ten seconds. This will reset the computer. Your 4matic WILL NOT work unless you do this. Even if you have the switch in the "on" posistion. Your 4matic light should still be on, so it must be a bad warning bulb