Battery light comes on on 1990 Buick Century

When I shift car into reverse the battery light comes on. When I shift into either neutral or drive, the light goes out. The light will also come on sporadically while driving. Car has new battery and alternator.

1 answer
the light is being caused by an alternator problem it comes one when it is not reciveing the right voltage at the battery. sounds like you have a wire not tighten enough on the alternator look for a red wire it should be a decent size wire try to wiggle it on the alternator if it is loose just tighten it down should fix the problem otherwise you have other electrial problems!!!!