Upgraded headlight harness blowing fuses

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xcmountain80

New member
I'm still working this out but I purchased an upgraded headlamp harness and installed it. Everything is wired correctly as far as I can tell but I keep blowing the primary (oem vehicle) 10amp fuses.

The DRL's were disabled years ago with what I believe was a wire snip. The fuse blows as soon as the selector is turned to headlights ON position. The fuse blows with intensity as a spark is visible.

Thoughts?
 
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make sure you don't have the power and ground leads reversed, it'll pop a fuse instantly and is pretty easy to do. I did it several times working on my projector retrofit.
 
Yupp, I agree with BlackCat.

You either have your (+) and (-) wired inversely.
Or, you have a short circuit somewhere.

Leave the fuse out, grab a multimeter and test areas nearest the battery, all the way to your headlight housing. See where the 12V stops.
 
Brian757 said:
Yupp, I agree with BlackCat.

You either have your (+) and (-) wired inversely.
Or, you have a short circuit somewhere.

Leave the fuse out, grab a multimeter and test areas nearest the battery, all the way to your headlight housing. See where the 12V stops.
Click to expand...

Multimeter should give me a clear picture as to what is going on and what is going wrong.

I am correct in assuming once the DRL is cut out (so many years ago) it is done and should have no repercussions... Right?
 
xcmountain80 said:
Multimeter should give me a clear picture as to what is going on and what is going wrong.

I am correct in assuming once the DRL is cut out (so many years ago) it is done and should have no repercussions... Right?
Click to expand...

That is correct, just trace the cut wire to make sure it isn't shorting on frame anywhere or anything like that. I cut my DRL wire as well, and haven't had any issues, but have crimped the ends to prevent shorting. It should be fine though.
 
The multimeter seems to have pin pointed the issue. I tested the stock 3 prong stock headlamp socket and plugged in but not attached to the bulb upgraded harness and got the following results.

I then tested the upgraded harness and got the following results.

Standing at the truck looking at the fire wall the three prong plug having a 9, 12, and 3 o'clock position.

The upgraded harness and stock harness have no power on 9 o'clock because its the high beam.

The upgraded harness and stock harness have power at the 12 o'clock position.

The problem I believe lies in the 3 o'clock position, the stock harness has no power and the upgraded harness has 12 + volts.

What are your thought?
 
Is the new harness for a DRL or non-DRL truck? The wiring is very different (switched grounds vs. switched hots).
 
TheDurk said:
Is the new harness for a DRL or non-DRL truck? The wiring is very different (switched grounds vs. switched hots).
Click to expand...

Dunno, it is advertised as for NON DRL. I stated prior to purchase that it was a DRL vehicle and is now not. Anyhow I switched the + to - and - to + and it works.....all of it, even the high beam indicator. So it works and headlamps are brighter.
 
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