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Auxiliary switch fuse blown, I think. Assistance please...

Jeffrey67

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I've had 2 LED lights connected to "switch 3" (15 amp) for a while, and decided to add 2 more lights to this switch. I assumed that LED's draw low power, so it wouldn't be a problem. I was wrong. I hooked up, hit the switch, and they all came on for about 5 seconds, and then they all went out. The switch button still illuminates when activated, but no power. I went to the manual and located "Cavity F103 15 AMP Blue fuse for HD ACCY #3" ...and it looks OK? Is there a second fuse for this circuit?
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Rhinebeck01

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I've had 2 LED lights connected to "switch 3" (15 amp) for a while, and decided to add 2 more lights to this switch. I assumed that LED's draw low power, so it wouldn't be a problem. I was wrong. I hooked up, hit the switch, and they all came on for about 5 seconds, and then they all went out. The switch button still illuminates when activated, but no power. I went to the manual and located "Cavity F103 15 AMP Blue fuse for HD ACCY #3" ...and it looks OK? Is there a second fuse for this circuit?
@Jeffrey67

Well, for Aux 3, it is F103 and a 15 amp fuse. You say "it looks ok" but is it for sure or not? Looks and is in fact ok are two different things..

For testing purposes (after you disconnect the lights that caused the overdraw) do try a
different 15 amp fuse. If you want swap fuses with F108 in the PDC, which is the 15 amp for Aux 4.

If it is not the F103 fuse that is problematic, look elsewhere for the problem. Are you sure when you / whomever did the initial wiring of the lights, did not leave/place an inline fuse on the power wire for the lights..

About your overdraw .... when the LED lights first switch on, draw is a small percentage greater then specs show.

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For those that read through this thread .....

With Factory installed Aux switches, here is the fuse list in regard to Aux .... Aux 1, 2, 3, 4, and also the Direct to Battery and Ignition Switched, wires which are only found in the passenger foot well, Aux bundle.

These fuses are found in the power distribution center (PDC) next to the Main battery.

F50 HD ACC — If Equipped 10 Amp Red Micro < Ignition switched wire in pass foot well

F72 HD ELEC ACC PKG — If Equipped 10 Amp Red Micro < Direct to battery in pass foot well

F92 HD ACCY #2 — If Equipped 40 Amp Green Cartridge < Aux 2

F93 HD ACCY #1 — If Equipped 40 Amp Green Cartridge < Aux 1

F103 HD ACCY #3 — If Equipped 15 Amp Blue Micro <Aux 3

F108 HD ACCY #4 — If Equipped 15 Amp Blue Micro <Aux 4
 
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Jeffrey67

Jeffrey67

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I reconnected to auxiliary two and the lights work perfectly. I will try switching the fuse later I ran out of time last night because it got dark. I’d be surprised if the fuse is bad because it really looks perfect but I will check.
 

DavidArmen

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Most Off-Road LED lighting use powerful CREE LED’s which do indeed draw a lot of current. I am almost certain you exceeded the maximum current rating for that particular auxiliary circuit.

It is very important to add up the current draw of each LED you connect to the same circuit to ensure you are 15%-20% below the maximum current rating, because current always fluctuates slightly.
 

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I’d be surprised if the fuse is bad because it really looks perfect but I will check.
Just a quick note on this. You cannot tell if a fuse is good or bad simply by looking at it. The only way to tell is by using a multimeter and performing a continuity test, or testing with a fuse tester.
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