for the last week, my reverse lights have been acting up. when i throw the car in reverse, they flicker on and off, sometimes not even staying on. i figured it would be a short somewhere. my cousin told me, however, that there's a switch or something that is tripped when the car is thrown into reverse, causing the reverse lights to go on. he said that if something is dirty then they won't go on...is this true or do you think it is just the wiring? anyway i can check it myself?