Recently killed my old headlight (Single H4) when it came loose and melted the housing...

So I bought this until I find something I like more:


It claims Dual Beam. I thought it was odd but I can get it to dim two of the bulbs as low but then only one works on High. Works fine with one bulb as high and one as low, but I'd like both!

Wiring on the old bike is just the 3 wires and it's a 2005 BMW K1200s streetfighter.

Any help would be swell, Joh

  • Welcome to Motor Vehicle Maintenance & Repair! You're saying you'd like both to either work on high beam and both on low beam, at the same time? – Pᴀᴜʟsᴛᴇʀ2 Jul 12 '19 at 19:41
  • It doesnt make sense to me. The way you describe it i think the bulbs are either on or off. 1 is a dedicated low and the other must be dedicated high, and you must be running both at the same time. Unless there is some hidden wiring whish switches the low/hi side when the 2nd light comes on. – Sir Swears-a-lot Jul 16 '19 at 19:20
  • Can you add a real photo of the back of it? – Sir Swears-a-lot Jul 16 '19 at 19:21

If either can go high at anytime while the other remaining low I would imagine that your bike can't provide enough current to the bulbs to put them in the same state. Do you know the max wattage of the single H4 vs the dual H1's?

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  • I don't sorry, it came with an aftermarket everything. I was just confused on how to connect them, as its only two wires to each bulb, one being ground, what determines how the bulbs react as to high or low? I've currently just got it so one bulb is on as low beam and both for high beam. But these are both on at full power so I'm thinking the bike can handle both at full?? – Joh Jutbauge Jul 11 '19 at 22:08

The problem is H4 is three pole bulb. So in the socket there is three holes. If the product in this website has corresponding plug to the socket in the motor, it will work I guess.

Does the socket in the motor look like that?

socket photo

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The H1 bulb is a single filament headlight. Low beam @ 55W). The H4 is a dual filament headlight configuration. Low beam @ 55W, High beam @ 65W. The base on each bulb is the ground connection. Each terminal connects to a filament on the bulb. These are the power connections(+) and are switched independantly. In a two light system it is not wired for high beam and low beam at the the same time. The light pattern of the beams are different. One is a symetrical beam pattern and the other one is a asymetrical pattern. I believe that having both beams operating at the same time would not be legal.

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