A friend and I just put a new cd player in my car and decided to self install it. After it was completed I was driving down the road and notice that the headlights wouldn't work. I went to the local volvo dealer and asked a friend that I have there, and he assured me it was the switch. I purchased the switch and installed it. No such luck. Still not functioning. The odd part is that my brights and parking lights work, though I have to hold the lever to keep them on. I've been told its a relay. Help?