I learned something interesting last night while changing my H13's. These lamps can be installed in multiple orientations. This can create poor beam focusing and irregular light patterns.

After installing, I always check high and low beams to make sure the lamps are good. When I hit the highs, one lamp pointed down and the other up.

So, I removed and replaced the lamps and tried different positions. In my truck, it matters which orientation the lamp has relative to the lamp assembly.

The H13 has a glass bridge inside the glass capsule. In the bridge there are 3 lead wires, 2 that are closer to one side. For orientation purposes, you need to split the head lamp into 2 segments. A top half and bottom half. Just mentally draw a horizontal line across the head lamp assembly that goes across the bulb.

If the lamp is positioned with the 2 lead wires in the top half. The high beam pattern is off. The high beam focus ends up being lower then that of the low beam. Now position with those 2 lead wires in the bottom half and the high beam focus is above that of the low beam.

Since it's so easy to do this, I tried both sides a few times. Each time the beam focus shifted.

Hope this helps

 

I always thought the bulbs where keyed to allow installation only one way? Thats been my experience.

 

That's been mine too. Until last night on H13's

 

thanks for the info man. I would never have noticed until it was dark out.

have to remember this for when I get some of those Silvanias