High/Low beam headlights

I recently replaced the bulbs for both Low and High beam headlights in my '99 Chevy Blazer. I used Sylvania Xtra Vision bulbs in the low beam and Sylvania Silverlight in the high beam. (The vehicle has composite lamps, separate reflectors for low and high, built into the same housing) My problem- the low beam and high beam aim are now nearly parallel. I’ve adjusted it to a “compromise” (the low beams are too high, the high beams are too low). Anyone else heard of this problem? What replacement bulbs would work the best?

Double check that it’s the right part # and seated correctly.

If this is happening on both the right and left side, I agree w/above that the bulbs are not seating like they should. There is a slight possibility tho that the vender has got a lot of bad bulbs. One time I purchased a fuse at a parts place which blew straight away, so I went back and bought another, and it blew straight away. After several hours of testing the electrical circuit, I decided this second fuses was bad too. I bought the third fuse from a different vendor and it has worked fine for 15 years.

The bulbs were each part of a “twin pack”, and the number corresponds to what the manufacturer calls for. My only theory is that the “Xtra Vision” bulb’s claim of more light is obtained by repositioning the filament slightly to throw the beam further down the road. Not exactly the effect I had hoped for.

Did you follow exactly the instructions on the package and what the shop manual says? Did you wear gloves when handling the bulbs? I know the icon-based instructions they use on those light bulb packages are close to impossible to decypher, so it’s possible something might be still be amiss in your installation method. Unlikely, but shouldn’t be entirely discounted. Maybe simply re-install them, see if you can twist them this and and that to get them to seat better, and see if it helps.

Also, the bulbs are quite a bit brighter when new than after a month’s use. They dim pretty rapidly, then level off and maintain a constant brightness after the break in period. So it’s possible the problem may go away by itself with time. I had this problem after installing a new headlight bulb on my Corolla, the new one was much brighter than the non-changed-one, I got some rather visible complaints of the digital nature from other drivers, but after a month they were pretty much the same brightness.

If you decide the new bulbs are just not going to work for you, you may find them to be difficult to return. If so, don’t throw them away. You can make a battery load tester with them. Headlight bulbs pull a lot of current, 20 A or more (on 12 V). To test the battery, measure the loaded vs unloaded voltage. The bigger the difference, the worse the condition of the battery. I saved my old headlight bulb for this as there was still one element working, and use it to test various household batteries, mostly for testing AAA, C, D cells, recharageables, etc, but could be used for testing 12 V car batteries too provided it is mounted properly so it is safe from breakage and can dissipate any excess heat.

I finally broke down and bought “Xtra Vision” high beam bulbs to match the low beam. They had a clear color glass, as compared to the blueish tint on the Silverlight; and, although the filaments looked identical, it must have been positioned to a micron or so difference, enough to “raise” up the beam of light. It seems the problem is solved now.

The extra light is actually obtained by tweaking the inert gas and filament to allow the filament to convert more of the energy to light rather than heat. Both the OEM and the Xtra Vision are 55 watts. My wild guess is that the Xtra Vision also uses a more pure tungsten, but that’s a guess.

It is possible that the filament is in a different spot in the bulb, which would affect the dispersion (pattern) and possibly the aim . Variation in the aim should be able to be adjusted out. If you’re uncertain how, the dealer’s parts guy (NOT the service guy) should be able to print out the procedure.