Funky problem with headlights

[WhiteNinja]

My son has a 1993 Nissan 240sx, the headlights open up and close just fine and he just changed the lamps to sealed halogen units. The problem is that when he turns them on, only one lamp will light. When he clicks the dimmer the lamp that is lit will go out and the other side lamp will light. So essentially as he clicks the lamps between high and low beam the lamps will light on either side but never both. I'm thinking this is the dimmer/lamp switch causing this, thoughts?
Modified by WhiteNinja at 12:00 PM 11/28/2005

[Magnes]

If he flashes his highbeams at night people will think it's a cop car and let him by.

Did this problem exist before he changed the lamps? If not, then he got a bad set of headlamps, replace them again. If the problem existed before then it is in the wiring.

[WhiteNinja]

LOL, yeah he thought that was cool at first until he's started getting pulled over for having a light out.

Ok, we will do some experimenting. I think it was doing it with the original lamps and that was part of the reason he replaced them.

Geez I hate wiring problems!