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Discussion Starter #1
Rather than add to an older thread that's recently been revived I'm starting a fresh one:

I want to have halogen driving lights on my JKU that can be both switched when I go to high beam and turned on/off independently, too.

Also, I'd like the lights to be fed from the battery through a 'key-on' relay so that I know the switch won't work unless the key is on. Through some research I've created this wiring diagram which I hope the hive mind will study and let me know if I've got some fatal flaw I'm not seeing...

Already installed is an H4 headlights wiring harness from Susquehanna Motor Sports (Rally Lights, Hella ) so I already have a 'sense' wire coming from the high beam relay to use in this wiring setup.

I also have a fuse tap I can take 12v from a key-on fuse in the fuse box itself to trigger a relay for both power and at the switch. (To be clear, not powering the lights from here; just the relay connections.)

I'm no electrician, so the logic that looks so, err, logical to me might be completely off track, and I'd like advice also on how to take this abstract diagram to reality: recommended wire gauges for 100 watt driving lights, best practices for wiring/gauges to use through firewall to On-Off-On switch, even brands to use/avoid, etc.



The Key-On Relay will probably become a power source for a little fuse block down the road when I want a couple more Key-On accessories, so it will be a fairly heavy load. Do I have the fuse in the right spot? Do I need fuses anywhere else?

Thanks!

Commo
 

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Looked real quick - one piece of feedback: I'd either fuse the 12v key on taps or be very careful to make sure they're on the correct side of the fuse in the fuse block. Easy to get them on the wrong side and disable the stock fuse you're tapping.

Also - your three way switch is only able to trigger when it has power from either the high beams or a keyed power source, the way you've got it set up here the key on relay is redundant.
 

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Discussion Starter #5
FingerTight: thanks for your good thoughts on the fuses; I will study that carefully. Since those two wires are feeding relay triggers would you keep them at 3 or 4 amps, or would you match the amperage to the fuse that's being tapped?

If I redrew the diagram I'd show the KeyOn relay feeding a fuse block (3-4 circuits) that I envision down the road a way...I think that would justify the KeyOn relay a little better.

OTOH, with this set up, the Driving Lights wouldn't come on at all unless the key was On, which is potentially helpful -- if I somehow left the lights on (with the key out) the Driving Lights wouldn't be a drain. Unlikely I know...

eguiyab: FT is correct. This setup allows me to have the driving lights on by themselves, not all that necessary, but good for aiming them if nothing else..

So in one 'On' position the 'sense' 12v from the high beam relay will tell the Driving Lights to turn on when I select High Beam. (This is a function that SMS will build into the wiring harness for you, but you have to ask for it..)

In the other 'On' position I could turn on the Driving Lights independently, for aiming mostly.

Hmmmm, I could even turn on the Low Beams/Fog Lights and run the Driving Lights at the same time...really light up the (off)road!

Commo
 

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FingerTight: thanks for your good thoughts on the fuses; I will study that carefully. Since those two wires are feeding relay triggers would you keep them at 3 or 4 amps, or would you match the amperage to the fuse that's being tapped? If I redrew the diagram I'd show the KeyOn relay feeding a fuse block (3-4 circuits) that I envision down the road a way...I think that would justify the KeyOn relay a little better. OTOH, with this set up, the Driving Lights wouldn't come on at all unless the key was On, which is potentially helpful -- if I somehow left the lights on (with the key out) the Driving Lights wouldn't be a drain. Unlikely I know... eguiyab: FT is correct. This setup allows me to have the driving lights on by themselves, not all that necessary, but good for aiming them if nothing else.. So in one 'On' position the 'sense' 12v from the high beam relay will tell the Driving Lights to turn on when I select High Beam. (This is a function that SMS will build into the wiring harness for you, but you have to ask for it..) In the other 'On' position I could turn on the Driving Lights independently, for aiming mostly. Hmmmm, I could even turn on the Low Beams/Fog Lights and run the Driving Lights at the same time...really light up the (off)road! Commo
Happy to help!
I'd match the fuse to the wire size. Since the relay trigger is relatively small I think you're on the right track with a small fuse. If I were wiring it I'd run one tap into a 5a fuse and then all my trigger feeds out the other side of the fuse.

Either way you wire it make sure you're choosing a good fuse to tap off of. Meaning - I wouldn't put a 5a tap on a 2.5a fuse in the block. I also would avoid tapping something like the defroster that draws big current for long periods of time. Something momentary and rarely used like the power mirror circuit is a good choice I'd think.

Makes sense regarding the key on relay, I assume that those 3 or 4 circuits would be live with the key or would they be feeding relays similar to your setup here? If the latter you may still be able to simply key the relay triggers. If not whatcha gonna have that turns on directly with the key?
 

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Discussion Starter #7
FT: Good info on the fuse tap..that is what I have in mind but may find some questions as I delve into it..

Yes, circuits would go live with the key, thinking about some small-draw lights for the interior rear, perhaps other lighting hookups, maybe a power source for my GoPro camera, etc.

Just day-dreaming about those kinds of things at this point..

Commo
 

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FT: Good info on the fuse tap..that is what I have in mind but may find some questions as I delve into it.. Yes, circuits would go live with the key, thinking about some small-draw lights for the interior rear, perhaps other lighting hookups, maybe a power source for my GoPro camera, etc. Just day-dreaming about those kinds of things at this point.. Commo
Keep us posted as you progress!
I'd like to have an onboard compressor that charges up a tank when I key on, install an air fitting at each bumper....
 
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