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Discussion Starter #1
Hey All,

I'd like to install a fuel pump kill switch as a safety/security precaution in my 2004 Xterra XE and wondered if anyone could provide some insight on the wiring. The idea would be to add an inconspicuous stock switch to the dash that would cut power to the fuel pump and prevent theft/car jacking, etc. We'll be taking our X through Mexico, Central and South America (and possibly beyond) this coming November and would like the extra piece of mind that we could surrepticiously disable the vehicle if we wanted. The fuel pump approach is preferable as a battery kill switch is more immediately obvious and easier to trace instead of letting them get a little ways down the road (and away from us!) before encountering a problem that could be caused by a lot of things.

My first idea would be to patch out of the fuel pump fuse near the driver's knee with an inline fuse and a switch. Of course, if someone removes the fuse panel to investigate, they would quickly see what's been done.

The preferred approach would be to tap into the fuel pump power source behind the fuse box but this requires knowing which wires in the harness are for the pump. I have the Chilton and am looking at the wiring diagram but could use a little help (see below).



Disclaimer: I'm learning this electrical stuff as I go but, it looks like the BLK wire is supplying power to the pump which connects to the relay and back to the fuse via the BLK/WHT. Would it make sense that finding the BLK/WHT and putting the switch there would do the trick?

Anyone have any other thoughts on how to achieve the desired result?

Thanks in advance for your input.
 

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Silver Submarine
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i wouldn't mess with the wiring if you don't know what your doin and just pull the fuel pump fuse before you leave the truck. Yea not as convenient as a switch but with the same effect.
 

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The black wire is the ground for the pump. The black/white wire is the power for the pump. Your best bet is to throw a relay on the ground wire and wire the kill switch across that.
 

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Theres a real simple way to do this. The fuel pump wires are under the rear seat on the passenger side, it wouldn't be hard to cut a lead and wire a switch inline. The hardest part would be running the two wires from the rear seat to wherever you want the switch on the dash. Just be sure the wiring is at least as big as the wiring going to the fuel pump now.

I'll post up some pictures in a bit.

-Clint
 

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Discussion Starter #5
Thanks for the responses, guys. XMike, I'm not quite ready to give up yet and while I'm learning electronics, am fairly handy otherwise. Seems like I should be able to just snip a wire and pop a switch in. I promise to send you a muffin basket if I find myself stranded somewhere 'cause of this.

Etoasty, your solution would definitely be the most clear cut, but yes, running the wires from the back seat seems like asking for troubleshooting hassles down the road if something dies. I like the idea of adding the switch right at the fuse box so it's easy to bypass if there's an issue.

Swordfish, now that I look at the diagram, my guess is that that black wire comes directly off of the fuel pump and grounds somewhere close. Still in the back seat. Do you see an issue with putting in a switch to interrupt the power on the BLK/WHT?

Thanks again.
 

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nope, no issues. you just want to make sure your switch can handle the power running through it if you aren't going to use a relay. if you don't, you'll toast the wires to your fuel pump and screw yourself.
 

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Well if you are handy with other things it wouldn't be hard to pull your front seats out and pull up the carpet enough to run the wires. If your worried about shorting and whatnot, put a fuse on the wire going to the switch. And troubleshooting is no problem... If it doesn't start go around back and bypass the switch. You have a really good idea with this one, if you give me a few days ill do this mod and do a write-up on it.

-Clint
 

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Discussion Starter #8
Hey Clint,

I'll be interested to see what you come up with though I guess I still don't see why to bother with the seat removal, running wires etc when there's access to the fuel pump power right at the fuse box. The fuel pump fuse is 15A so a 30A switch from Kragen should be able to handle the power no problem. What am I missing?
 

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Well that does make sense. I just like to have real clean and secure wiring. Unless I can find the fuel pump relay just sticking wires into the fuse block is a no go for me. But that would work though.

-Clint
 

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It seems to me the best location for a tap in would be the blk/wht wire running from the fuse to the relay.

Why? It's low amps isolated away from the pump circuit and switching a ground generally results in less arcing.

What I would do is look for the fuel pump relay. I believe its up under the dash above or near the parking brake. You will then see a thick blk/wht wire and a thin blk/wht wire running to the relay. The thin wire is the one you want to interrupt with your switch. Run a loop of wire with your switch good to go.

Tapping the wiring at a different location would be higher amps and cause more arcing on the switch. So I wouldn't recommend pulling the fuse and then using a tapper with wires or relocating the fuse. Not only is it messy and less safe but its super visible and easy to override if the thief was to pop the cover.

If you wanted to you could even for the ultimate in stealth use a magnetic switch. Place the switch behind a dash panel and give it a swipe with a magnet before you start it. You could even leave the magnet in plain view the thief would have no idea what your secret is.

The other option is to interrupt the ignition. Which would cause nothing to happen after you turn the key. Put your X in drive and turn the key, nothing happens. So if you were to want to interrupt ignition I would take a look at the park neutral switch circuit. I'd actually would recommend this over the fuel pump. Why? The thief would think its his error. Where as with the fuel pump switch the engine would still crank which would lead him to believe the truck has a burnt fuse or tapped wiring.
 

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Good ideas. If you do switch off the fuel pump relay and then accidentally try to start it with the switch in the off position, will that make the computer throw a code or light?
 

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Nah it doesn't. I've pulled my fuse and tried starting it, no code. If you keep trying it might but it should self-right.

-Clint
 

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Discussion Starter #13
Kill Switch Update

An update on this project... I decided to proceed with the simple approach of installing a switch right off the fuse box in the dash. I called the local dealership's parts department and tried to explain what I was looking for - basically, a dashboard switch that didn't exist in my 2004 Xterra XE. He found something to do with traction control or something (VDC, VTC?) but the switch was $45 and had to be ordered.

Frustrated, I did a Google search for junkyards near San Francisco, figuring I'd probably have to drive an hour or so to find one outside of the city. Amazingly, a result came up for a place down in the Bayshore, probably 5 minutes from my house. Even more amazingly, when I called, they said they had a 2001 Xterra. I figured the dash would be mostly the same and headed down the next morning.



I found the truck amidst the piles of junkers. It'd been pretty well picked over and showed brutal scars of the accident that put it there. Burned out seats, missing rear panels, and the dash hanging by wires. But right there, in one of the dash cutouts was a switch that was gonna work perfectly. And the weirdest part is that if this junker had been a 2004 like mine, it wouldn't have been there. A few (well, more like 50) hacks with the serrated edge of my car key and $10 and the switch and harness were liberated from the accident scene.



What turned out to be the perfect switch was actually a rear windshield rocker switch with an momentary up to activate the wiper fluid and an on/off down position that had been replaced in my 2004 with a stalk mounted control near the steering wheel. While the astute would-be car thief could *possibly* notice the duplicate rear wiper control, based on the number of windshield wipers swatting away on a dry day outside a rental car lot, I'm not that confident in people's ability to intuitively comprehend these controls.

Admittedly, I got intimidated about installing it myself and brought it to a local shop to wire up. Once installed in my truck, it looks like it's been there forever (lower left switch in the picture below) and works perfectly (as evidenced by the few times I've forgotten to turn it on). Plus it's position low on the dash near my left hand makes it easy to surreptitiously kill the pump if needed.

 

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Discussion Starter #15
I don't really know how it's wired but I suppose I really should. Just haven't wanted to mess with it but you've motivated me to take off the lower dash panel and have a look. I'll let you know what I find as soon as I get a chance to look.
 

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That's pretty cool, dude. Props to you.
 

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Why not a kill switch on the battery? Had one on my Zuki and it worked well.
 

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Discussion Starter #19
Why not a kill switch on the battery? Had one on my Zuki and it worked well.
Answer is in the first post of the thread. No power gives an immediate indication of the problem and hence a path towards bypassing the kill switch. The fuel pump kill could look like out of gas, bad pump, no spark and I imagine a whole host of other things. I'm just trying to stay one step ahead and be as annoying as possible to anyone who wants to ruin our day...
 
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