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Old 10-19-2018, 12:33 AM
Nanoda Nanoda is offline
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Low voltage (~9.3V) on car headlight - any recommendations?

My 2011 Ford Fusion is only registering ~9.3 V on the headlamp connector, when I'm imagining it should be up around 12. This is a problem as that doesn't seem to be sufficient to activate the aftermarket HID lights currently installed. I'm not the best with cars but I dabble with electrical stuff, so is there anything anyone can recommend I check?

Other info: I didn't install this system, and it worked for about a year after I got the car. Also while they don't turn on at all now, the problem started as an intermittent one, so the problem isn't blown bulbs.
I measured the low voltage on the connector, but also to the battery terminal which I gather indicates that it isn't a bad ground?
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Old 10-19-2018, 12:36 AM
kaylasdad99 kaylasdad99 is online now
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Which side headlamp? Is it the same voltage on both sides?
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Old 10-19-2018, 01:00 AM
Rocketeer Rocketeer is offline
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If your Fusion's battery measures 9.3 volts across the terminals with the engine not running, it's probably bad; normal should be about 12 volts. If it measures 9.3 across the terminals with the engine running, there's something wrong with the charging circuit (alternator); normal should be about 14 volts.

If the battery voltage is normal, but voltage at only this particular headlight is low, I'd suspect a bad connection somewhere.
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Old 10-19-2018, 06:16 AM
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Crafter_Man Crafter_Man is offline
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Measure the battery voltage - at the battery - when the car is not running. And then measure the battery voltage when the car is running. Report back with the results.
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Old 10-19-2018, 06:39 AM
jz78817 jz78817 is offline
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First thing you should do is throw that aftermarket HID junk in the trash where it belongs. The wiring in that car was not designed for it and has now been overstressed. You likely have an interim connection between the headlamp assembly and the power distribution box which overheated and is much higher resistance than it should be.

Sorry, but youíre going to need someone skilled in electrical repair to trace back all of the circuits. And when thatís fixed, put the correct halogen bulbs in there and donít repeat the previous owners mistake.
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Old 10-19-2018, 09:25 PM
Nanoda Nanoda is offline
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Thanks for the replies!
The 9V is while running - the voltage not running is lower - 8.4V. The battery itself is 12V not running, 14.3V running (pretty sure this is normal?). In this setup, it seems that the lights are relay-activated by the driver headlamp (the current for the HID lights themselves is provided by separate wiring directly to the battery.). The passenger side is going to take a bit to get to but I'll see if I can measure that somehow.
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Old 10-19-2018, 10:17 PM
BobBitchin' BobBitchin' is online now
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I would read the manual. It must have test procedures.

How do we know what voltage the lamp wants to see? Maybe 9v is right.
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Old 10-19-2018, 10:22 PM
excavating (for a mind) excavating (for a mind) is offline
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Quote:
Originally Posted by Nanoda View Post
Thanks for the replies!
The 9V is while running - the voltage not running is lower - 8.4V. The battery itself is 12V not running, 14.3V running (pretty sure this is normal?). ...
This pretty much confirms jz78817's diagnosis.
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Old 10-19-2018, 10:47 PM
K2500 K2500 is offline
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Quote:
Originally Posted by excavating (for a mind) View Post
This pretty much confirms jz78817's diagnosis.
Not if the factory head light wiring is now only a relay trigger, as mentioned.
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Old 10-20-2018, 02:52 AM
jz78817 jz78817 is offline
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Not if the factory head light wiring is now only a relay trigger, as mentioned.
Then the relays are junk. Seriously, these aftermarket HID kits are garbage; they may have capsules from legit sources but the rest of the kits are cheap junk. Plus, the optics are all wrong for HID capsules.

You should never, EVER put HIDs or LEDs in housings meant for halogens. Throw the shit out, put the correct halogens in, and call it a day.
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Old 10-20-2018, 11:01 AM
Gary T Gary T is offline
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Originally Posted by kaylasdad99 View Post
Is it the same voltage on both sides?
This is a pivotal question for any serious attempt to fix the issue.
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Old 10-20-2018, 11:17 AM
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beowulff beowulff is offline
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FWIW - I put an aftermarket HID kit in my Santa Fe.
There was no issue with voltage or current, but the beam pattern was terrible.
They were bright, but had bad off-axis hot spots. I'm sticking with tungsten lamps until someone comes up with a better HID capsule design.
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Old 10-20-2018, 11:29 AM
K2500 K2500 is offline
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Quote:
Originally Posted by jz78817 View Post
Then the relays are junk. Seriously, these aftermarket HID kits are garbage; they may have capsules from legit sources but the rest of the kits are cheap junk. Plus, the optics are all wrong for HID capsules.

You should never, EVER put HIDs or LEDs in housings meant for halogens. Throw the shit out, put the correct halogens in, and call it a day.
Maybe so, I don't have much experience with the product in question. I'm simply addressing the fact that it's unlikely that the HIDS overstessed the factory wiring since the factory wire in question was used only to drive a relay(per OP). Of coarse if the relays are junk, and if the headlamp circuit wasn't properly protected, then I could see a relay or it's coil failure causing some problems.

I've got led head lamps in my Harley and I like them. I can't imagine what would make them so undesirable that I should switch back to halogens except maybe the optics you mentioned.
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