[cujotom]

Check to make sure that they are both the same headlight bulbs. I had the same problem,( lights just turn off than come on). I found that 1 of the bulbs was diffrent than the other( Thats one of the reasons they say replace in pairs) It had a diffrent watt rate and it made my headlights do some strange things. Also if this is the case while you are driving with your lights on is your relay in the fuse box super hot? If so replace your headlight bulbs.