Mad Chemist

Well, after hearing about two different toyotas getting stolen recently (one in OR, one in FL), I became sufficiently paranoid that I wanted to install a hidden fuel pump cutoff switch in the vehicle to add to the Viper car alarm that I have.

Gadget was nice enough to identify the wire coming from the fuel pump for me, so I proceeded with the following procedure:

1) Remove the trim plate in the REAR seat, driver's side door. Assuming that a thief might look for wires leading from the front seat, I decided to put all the wiring further back in the vehicle.

2) The fuel pump wire is blue and orange stripes (in my 98 4X4 SR5), and there weren't any other wires even close to this color combination. To double check, with the key in the on position, without the vehicle started, I couldn't detect any current. With the vehicle running, current! The final check was to cut the wire and see if the vehicle ran (it did not), resplice and check again (it started just fine). The fuel pump wire runs through a bundle of wires,coming from the center of the vehicle, that joins with the main bundle running along the side of the cab. This means that once you've removed the trim in the back seat, if you look too far towards the rear of the vehicle for the blue/orange wire, you won't see it- you've got to look after the two groups of wire join.

3) Once you've cut the wire, its just a matter of running a switch. I wasn't sure what kind of draw the fuel pump had, and am also not real versed on electronics, so I just went with the switch with the highest amp rating I could find at Radio Shack (I think it was 10 ams at 125 VAC, but I'll have to check). Before the switch, I added a 5 amp blade-type fuse holder

3) Run the switch under the carpet to a secret location that you are not going to tell anybody about! Ahh, did I mention that I did this on a "friend's" vehicle.... P.S. Don't tell anybody!!!!

The advantage of this type of switch (unlike one for the starter), is that the vehicle will still try to start normally, and may confuse the average thief looking for a quick joyride. Assuming that they're going to look for switches in the front seat, put it someplace a bit more out of the way. Yes, it'll be more of a pain for you to use it. For me, it'll likely only be used when I'm in sketchy neighborhoods or when I have to park at trailheads. As a safety factor, I would tell people I'm hiking with where the switch is, only if I'm the only one that drove. If I get hurt/incapacitated, and they need to drive and get help, they need to be able to start the vehicle.

Perform this mod at your own risk, I'm not responsible, blah blah blah. I did not invent this mod, this has been around for a long time.

AznSky

that actually sounds like a really good idea. I'd consider doing it if I wasn't so mechanically/electrically illiterate.

SteveS

Sounds Good, You most likely slowed them down enough to send them elsewhere. Someone tried to steal K-Blazer, but a simple mod like yours kept my truck where I parked it. Good, Clean sonding job.

ZR2Steve

Albuquerque Jim

Has anyone done this on a 2000 SR5 4X4? I just wonder if it's the same color wire. I am going to check today.

turboale

My dad did this in his old Saab 99T. He had a three position switch though and he put a red LED in the dash. The switch positions were On, Off, Off-blinking led. Of course those were the days where car alarms were complete poo. Good job! Wouldn't be a bad idea. My lumbar isn't working anymore... would be kind of cool to use that switch... hum....

PS, I love the new avatar... Have you considered connecting them to your interior lights so when you unlock the truck they come on? Ive been wanting to do that mod for that reason. Thought that would be pretty trick. Or since you have a viper you could use one of the aux switches...

Mad Chemist

I'm thinking the wire colors are probably the same. I just cut and made sure the vehicle turned over but didn't start. I've got the switch very far from the front seats. Its a pain to open the rear hatch to get to it, but a whole lot less likely to be found by a thief looking for a fuel cutoff switch.

At the moment, I haven't done much else with the lights since I installed them. I've yet to put them on a relay yet, so the switch starts getting pretty toasty after the lights are on for a few minutes.

I've thought about getting them wired up to the Viper, but I would probably have to take it in somewhere to get it done? The car came with the alarm, so I don't have any of the wiring diagrams or anything.

Unhappy99

If you connect a relay or SCR inline then you don't have to run power wires everywhere.

If you cleverly connect this relay or SCR (silicon controlled rectifier) then you can get an automatic resetting fuel cut i.e. turn off ignition, relay/SCR disables, and won't enable until the button is pushed while cranking. Don't have to hold the button down while running, and then disables again with ignition off.

Mad Chemist

I'm not sure I understand- don't you still have to connnect the relay to the button, via wires? Honestly, it was a breeze to do.
Your setup, while an interesting idea, still requires that you have a button somewhere close to the driver's seat to start the vehicle. Therefore, any thief looking for a fuel cut-off switch of some point is going to look for it/find it. My whole goal was to move the switch as far from the front cab as possible.

Unhappy99

The fuel pump draws several amps. What I mean by not running power wires is that you can place the relay/SCR close to the broken pump wires, then run low current (30 milliamps), and hence light gauge, wire anywhere else to engage the relay primary or SCR gate.

Getting clever about where you place switch is up to you. You may not even need an independent switch, but could tap into existing wiring and have it set up so that the rear window must be down, ac fan on, headlights on, turn signal left, etc. or any combination thereof.

waskillywabbit

iTrader: (-1)

Unhappy,

I don't undestand why you'd go to the trouble of wiring it in such a way. A simple switch in an out of the way place seems like the simplest and most straight forward approach to what David is trying to do. Besides, if you had it with some combination of what you suggested you'd look like I did when I was trying to reprogram a remote and opening and closing doors and locking and unlocking, the neighbors will think you've lost it! Many times your first intuition is the right one.

We want to see some pics David when you get done! Or would that give away where you put the switch putting up a picture of it on a widely surfed forum?



Brian

Unhappy99

David's solution is good for what he wants. He says himself its a pain, and would likely only be used in sketchy neighborhoods and trailheads.

If that's what you want, great. Except I would place an SCR or relay inline and run low current wire to the switch.

What I am describing is something more convenient for everyday use. A self-resetting device which requires a secret switch close during start. You get to select what switch or combination will activate the pump kill, which could be your own hidden switch, or tap into existing circuitry.

Perhaps it would only start if the lighter was plugged in? The trigger switch is only up to your imagination.

Mad Chemist

I've actually already done the mod a couple months ago, but prefer not posting pictures of my "secret" switch on the internet. Probably wouldn't be too much of a secret after that....

Albuquerque Jim

Unhappy99,

Would you be willing to help me wire that up? I like the idea of a "trick" switch.

PhxTRDRunner

Sorry Guys, but Unhappy has the correct answer here. First of all, any way you do it should involve a relay. Fuel pumps are very dependant on voltage, and putting a switch in between the power source and pump is definately going to cause a drop in voltage. A relay on the other hand has very very little such drop.

The idea of making it so something had to be done, lights/windows, ects...very factory appearing.

Mad Chemist

I used a switch with an inline fuse, no relay at all. If there is a voltage drop, it is miniscule as I have not noticed any effect on performance.

doc_nomad

You could use a relay and reed switch. Put a relay in the line, then run the wire to the dash, the reed switch is put behind a plastic panel somewhere and when a magnet is placed on it, it closes the switch. The drug runners use this to hide the opening switch for thier secret compartments.

OneTrickToy

I was just about to say the same thing as doc nomad. A lot of cars that I ran into at the SD Auto Auction I worked for in cali had magnetic reed switches hidden in all sorts of places. Always kept the inspectors on their toes trying to figure out how to start the repo'd cars.

But what I'll add... you do NOT want a fuse/switch inline on your pump. ALWAYS use a relay on any sort of electronic device that is needed for your vehicle to operate normally. Reason being, what happens if your switch is accidentally flipped or your fuse blows out while driving? You'd have your cutoff backfire on you and you'd be the one without power. However with a relay setup like happy was explaining, the switch is only active when the vehicle is started. Relay's are reliable and less prone to failure or accidentally opening.