Mystery voltage in H4 high beam circuit

[Rob_in_TO]

So I installed a new set of H4s and used the relays to take the load from my light switch.

All seemed fine however I noticed the other day that the high beam circuit is charged with about 6 volts when the low beams are on. I did some investigating with my voltmeter and it seems the excess power is coming through the H4 light bulb when the low beams are on.

I have it all wired correctly to the best of my knowledge - I have even removed the relay from the high beam side so I know its not getting powered from there. Also, I removed the fuses for the high beam circuit and the voltage is coming from the load side when the low beams are on. This voltage feedback only happens when the bulbs are plugged in.

Is this normal? I dont a lot about 12 volt circuits but it seems to me the voltage shouldn't be feeding back like that.

Anybody?

[Flat Six]

Could be a manufacturing defect in the bulb, but not likely. Easy way to check is to swap out another H4 bulb. Do you get the same result on both (L/R) sides?

Given description of what you've already tested/diagnosed, I'd suspect your wiring -- especially where you spliced in the H4 sockets.

Hope this helps.

[sennasixty8]

Recheck the wires into bulb sockets. I bet low beam grounds are mixed up, sending current to the wrong side of the bulb

[HawgRyder]

Yup...sounds like the 3 pins have been incorrectly wired.
There is one ground..common to both filaments...and then the top side of each filament...one for high,,,the other for low.
If the ground and low get mixed up...the current has to pass through both filaments to get to ground.
Easy to do when replaceing the sockets.
Bob

[Rob_in_TO]

Thats exactly what it is guys - the wires were not wired into the connectors correctly.

Thanks very much to all for the input - what a great site this is!!

[dshepp806]

Not quite a mystery, afterall....... this board rocks!

BEST!

Doyle