charging light on.

hey guys my brother in law's just bought a 96 prelude (h23a1) apparently alternator has been replaced with an accord one. seems to work fine but the charging light (battery symbol) is on. unpluging the alternator gets rid of it but as soon as you plug it back in light comes on again.

anyone know of a way to get rid of it? is it just a case of rewiring the plug or is it a difference between the prelude and accord alternator?

any ideas would be great.

does abs light come on too?

yes abs light is on, if u unplug alternator n plug it back in with the car running it goes out. but if u then turn the car off then back on its back...