I herd H4 has higher wattage bulbs.. But was wondering i know how to hook up H7 to our car but the H4 has three prongs. Whats the third for?? How would i go about rigging this up?

 

H4, doesn't it have both the high beam and low beam in the same bulb? The other prong could be for the other filament.

 

The H4 bulb has a low beam and high beam filament. Thus, it has two positive prongs (one for low and one for high beam) and a common ground prong.

Also, look at the actual lumens output and not just the wattage.

 

Hmm... two possitives eh.. So id only have to use one cuz i only need it for one houssing correct?

 

One housing...what?

H4 has 3 prongs
* one prong is the positive for the low beam filament
* one prong is the positive for the high beam filament
* one prong is the common ground for both filaments

To turn on the low beam filament, wire up the low beam positive prong to a positive 12volt source and the common ground to a good gound.

To turn on the high beam filament, wire up the high beam positive prong to a positive 12volt source and the common ground to a good gound.

To turn on both filaments, wire up both positive prongs to 12volt sources and the common ground to a good ground.

 

Ya thats what im sayin.. In my formula either you have it hooked up to the low beam or high beam.. cant do both they are seperat housings.. (lamps) So i just need to wire it just like the H7 no dif just extra prong for other vehicle wich use the same bulb i understand now.. You like the boards light bulb geniuse guy! youve got an answer for all my lighting questions! thanx!

 

Just curious, but a H4 bulb will fit in an H7 housing and all you need to do is re-wire the harness?

 

You are welcome.

I think they are different sizes. If you are making your own housings though then you can probably make them fit.