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Discussion Starter · #1 ·
So I've seen it mentioned before and have been searching for the past 2 days looking for a definitive answer on the topic to no avail so here it goes...

I just swapped out my entire stock roof rack on my P4X for a Front Runner. In doing so, the "roof boob" lights came off with the stock rack which is not a big deal, but I do want to replace them. My plan is to run 4 round lights up top on a custom aluminum wind deflector and plan on running a 8 gauge + line from the battery to a pair of 40 amp relays that will each power 2 lights. I'll run another 8 gauge ground line and attach it somewhere under the headliner. Everything up to that point is no big deal... But...

What I want to do, so I don't cut out the stock roof lights wiring harness is use them as the remote leads for the relay triggers and use the stock switch. I don't mind that they need the brights on to activate the switch and have done the high beam / fog light mod so all the lights work together.

What I don't know is:
The plug on the stock harness has 6 pins. There are 3 wires per light which are (+),(-) and the wire for the magnetic switches in the stock light covers.
  • Can I just use the + wire from each to trigger the relays?
  • Does the BCM freak out if the (-) and magnetic switch wires are not hooked up?
  • Should both the (+) and (-) be hooked up (+ as trigger and - to ground)?
  • Is the magnetic switch signal open or closed? (That would determine if those wires need a signal or not.)
Any help from someone who has experimented with this type of setup would be greatly appreciated!
 

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I've done a ton of relay wiring on the X but don't have the boob lights so no experience there.

But from what it sounds like you could just use a multi-meter to detect which wire outputs 12v when the lights are supposed to be activated, you should be ok to reuse the ground wire as well just make sure to test it too as sometimes Nissan uses switched grounds on certain things.

The route I would do is just leave the factory harness there, since you plan on routing a power wire up there anyway just do the relay under the hood triggered by the high or low beams, whichever you prefer and run a single power wire up there for the lights and then use the factory ground. Then you don't need to mess with magnets and whatever other complexities it might involve.

You haven't said what the wattage of the lights is but I doubt you need two relays for this, most of the time a single good quality relay (not no-name ebay junk) will do the job.
 

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Discussion Starter · #4 · (Edited)
I've done a ton of relay wiring on the X but don't have the boob lights so no experience there.

But from what it sounds like you could just use a multi-meter to detect which wire outputs 12v when the lights are supposed to be activated, you should be ok to reuse the ground wire as well just make sure to test it too as sometimes Nissan uses switched grounds on certain things.

The route I would do is just leave the factory harness there, since you plan on routing a power wire up there anyway just do the relay under the hood triggered by the high or low beams, whichever you prefer and run a single power wire up there for the lights and then use the factory ground. Then you don't need to mess with magnets and whatever other complexities it might involve.

You haven't said what the wattage of the lights is but I doubt you need two relays for this, most of the time a single good quality relay (not no-name ebay junk) will do the job.
Thanks for the reply!

I actually think I have it figured out. The hot wires from the stock lights work without any other wires being hooked up but you need both sides of the connector to be plugged in for whatever reason. Not sure if that has to do with the magnet switches or not, but when I checked the + leads with a multimeter to the old harness with nothing else attached, it gets power but not when going directly to the truck side of the harness. Guessing this means the magnetic switches need to be grounded, which after unwrapping the OEM light harness they appear to share the ground line with the 2nd light.

I just ordered a spare 6 pin male connector like what is used on the stock roof light harness and plan on running the (2) + wires to (2) 40amp relays in a junction box under the rack which will each control 3 lights. Since I will be running (6) 120w round LED's which draw about 8amps each, I figured I would split the power and still have enough overhead in case I want to go to a more powerful set of lights in the future.

I'll be running a 4 gauge + from the engine bay, up the drivers side pillar and through the existing roof grommet to the junction box. From there I'll split it to (2) 8 gauge lines to the relays and run the output to (2) fused distribution blocks and then to the lights. For grounding I want to keep everything up top so I am only pulling 1 wire from the engine bay to the roof.

The good news is this will be the most complex wiring on the rig since I also just installed a Trigger Six Shooter bluetooth control module which has 6 circuits and should be more than enough for what I plan on doing. It also eliminates the need to wire any switches inside the cabin since it's switch panel is bluetooth and is battery powered unless you decide to hard wire it to control backlighting.
 

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Discussion Starter · #5 ·
I'll just marked this as solved:

With a single 0 gauge hot wire running from the battery to the roof into a custom distribution box that splits to (2) 40amp relays I was able to get the stock P4X roof light wiring harness / OR dash switch to work as the trigger.

I ordered a 6 pin connector from Wiring Specialties here:


On that harness the top 2 wires are for the magnet switches and don't need to be used. The bottom 2 sets of wires (side by side) are the + / - for the stock lights. Just run one + to each of the relays switch terminals and run the - to a common ground (I used the distribution block). Everything works just like the stock functionality of the "roof boobs" (just much brighter).

(Rooftop Distribution Box - Pink / Green are - and Blue / Yellow are + on the 6 pin connector)
122911


(6 Lights running in (2) circuits of 3 lights - each triggered by 1 of the original light circuits)
122912
 

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I'm glad someone else has already figured this out! I was thinking of doing something similar on my P4X, swapping to the Frontrunner rack and then adding more powerful lights.

Question - are you getting much glare inside with those lights? I had big Cibie Oscars on the front of my Wrangler that really did the job driving through Baja, and my basic usage is just to light up way out ahead of me in the desert.
 

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For future reference for anyone attempting to do the same thing.

Stock roof light harness.

~ White/red is power
~ Black is ground
~White/green and blue/white magnetic switch

To get the existing off road light switch to work you need the above mentioned Nissan 6 pin harness. Run the white/red to activate the relay. The black to the ground of the relay. And do nothing with the white/green and blue/white. Leaving these two wires alone will trick the BCM to think the light covers are off.

Special thanks to Nex and six60six for your help.
 
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