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Identifying Halogen Replacement Bulbs |
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There are two series of Headlamp bulbs used in the US - One is the European series of bulbs known by the designations H1, H2, H3, H4 and H7. The other series is the 9000 series of bulbs designed for use in composite headlamps. So how do you know which your headlamp uses - If your owners manual is of no help and the dealer can't tell you the type of bulb, you may have to pull them and read the numbers on the bulb base. If you have a US composite headlamp, look at the lens of your headlamps and you may find one or two HB designations molded in the glass/plastic. Generally the designations are near the associated bulb. The equivalencies are as follows:
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The 9004 and 9007
are dual filament bulbs so you will have one one bulb per side. |
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Just casually looking at these two, the difference is not readily apparent but in the 9007 filaments are vertical and in the 9004 the filaments are horizontal. The bases are near identical except for the keyways for assembly with the lamp and the keyways for the plugs. |
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| The 9005 and 9006 are single element bulbs and are high and low beam respectively. You will have two bulbs per side - one 9005 and one 9006. The difference here is a little more apparent. The 9005 has no cap and is used as a high beam bulb. The 9006 has a painted cap to block the light from leaving the bulb straight ahead and is used as a low beam. Other than that, there are slight differences in the keyways for assembly with the lamp and the keyways for the plugs. |  |
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These are the H1, H2 and H3 bulbs. The H1 is starting to be used in late model US DOT lamps as both a high and a low beam. The H3 is very common in auxiliary lamps - Fog or Driving. The H2 in an uncommon bulb and is found mostly in older auxiliary lamps. It is a very efficient bulb but mounting is difficult and requires a ceramic holder. |
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This is
the H4. A very common dual element bulb providing both High and Low beam
elements. The internal shield is under the low beam filament and by
reflecting half the light, helps provide the characteristic sharp cutoff of a
European lamp.
In some recent vehicles, one element is used as a High beam and the other as a Fog beam. In this application, there is a second bulb for the Low beam. |
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This is the H7. By now you recognize the paperclip. This is
a relatively new bulb appearing first in 1995 BMWs and Mercedes. The H7 is
becoming more popular in late model applications. Upgraded bulbs are hard
to find because there are so few in use (relatively). The market is simply
too small for a major bulb manufacturer to develop and market derivatives.
This particular bulb is a Hella High Intensity Plus, now discontinued. In the light used for this photo, the bulb appears Blue. It is a coated bulb that may look different colors in different light. It depends on the dichroic effect at the boundary of the different layers of coating to influence the color of the light. This particular one puts out a white light with a sometimes orange halo. Coated bulbs are strictly cosmetic. |
To get more information go to
Susquehanna MotorSports
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Copyright 2004 EndoSquid Productions
Page last updated: October 5, 2001
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