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HQ Single Headlight Wiring Issue

Hi Guys- I'm a bit stuck with this one.

HQ Ute, single headlight front. Since starting to drive it again i haven't had low beam working. The high beam works no problem as do the park lights. Naturally i tested the lights by running wires directly from the battery positive and negative to the lights- low beam still works that way.
I checked the light sockets and am getting 12V for both LH and RH, yet the light will not work? I have made sure to run wires from the battery to the corresponding connection in the socket, yet there is absolutely no response when the socket is on the light.

It seems all is working as it should, I'm just not getting any low beams?

Any ideas?

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Comments

Inside the beam (or bulb), both filaments shaere one earth.

If the earth is lost, one filament earths through the other filament.

It's a common problem with OH tail lights.

http://holdenpaedia....

http://holdenpaedia....

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T

My Shed

Holdenpaedia, they're the brakes Mate.

Thank you T, i will replace the headlights and see how i go.

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I think what T is saying is check your earth, 90% of light issues on old holdens are caused by bad earths

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Understood, thank you for the clarification

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Check the dipper switch too, not unusual for the contacts to burn out in them. I replaced mine recently because it was stuck on high beam.

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Cheers
David

aka hq308belmont

My Archived Shed

Thanks David i will check the switch

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How are you testing for 12v?If using a digital multimeter to test DC you cn get a false reading.Better off using a test light.
Cheers,Chris.

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i have been using a multimeter but i will give a test light a go, cheers chris

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You will only get a strange reading with a digital meter if your engine is running, as they have a very high input impedance. Your dimmer switch has 3 terminals, (power in, lo beam & hi beam). If you remove the plug, turn your lights on, and check between ground and any of the pins, one should have 12volts. That is your power in. By shorting that pin to any of the other 2 remaining should bring on those lights. The dimmer switch is usually the culprit.

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"If your car has quarter vents, a diff at the back, and was available with wind-down windows, you may talk to me.
Otherwise I am not interested. Amen."

Another problem with digital meters occurs if the switch gets an oxide fleck on the contacts.

Let's say the fleck has a resistance of 1000 ohms and the meter has a resistance of 1000000 ohms. The fleck will stop the light working, but the DVM will still read full voltage.

That happens because the highest resistance in the series circuit takes the greatest amount of voltage.

In this case the DVM will take 99.900% of the voltage and the fleck will take 0.1%.

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T

My Shed

Holdenpaedia, they're the brakes Mate.

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