Stereo & Electronics - Fuel pump kill switch

Im going to put in a kill switch for my fuel pump. I suppose more than a few times I or someone else will try to start the car without turning the switch on, can that hurt anything?

I want to use a normally open momentary switch. That way I just press and hold the switch, start the car, and release the switch. No need to press the switch again when I shut off the car. How do I wire this up, I tried to figure it out with some relays but couldnt?

Im also going to have a "valet switch" so I can disable the kill switch when I take the car in to have work done....a toggle switch in parallel with the kill switch should accomplish that.

the wire and relay for the fuel pump is by yourt left foot under the door trim panel...put a on off switch in the ground for the relay

if you use a momentary switch wouldn't the fuel pump turn off when you let it go after the car is on? no fuel = stall?

if you use a momentary switch wouldn't the fuel pump turn off when you let it go after the car is on? no fuel = stall?

Yes, if it was just the momentary switch and nothing else. Im trying to figure out how I can use a few relays etc to make it work.

Ideas anyone?

A momentary switch can be used with a "latching relay" to activate a circuit that will remain active until the power is removed. Your rear defogger is sort of a latching relay except that it also has a timer to shut it off. Pressing the defroster button activates the circuit and it stays on until the timer shuts it off (or you turn off the car).

Here is a thread that shows how to make your own latching relay from an ordinary automotive "Bosch" style relay and a diode: http://www.ls1tech.com/forums/showthread.php?t=681569

You would put the latching relay inline in the fuel pump relay circuit. Use an ignition controlled power source (so that it will shut off when you turn off the ignition) and use your push button to latch the relay. You would have to turn on the ignition then press your button to activate the fuel pump before you could start the car.

Using an extra factory ASR switch (TCS switch on Firebird) would be a good way to hide its function. You would have to be sure to hide your "valet" toggle switch someplace that isn't obvious or even easily accessible.

Thanks! This is just what I was looking for.


You would put the latching relay inline in the fuel pump relay circuit. Use an ignition controlled power source (so that it will shut off when you turn off the ignition) and use your push button to latch the relay. You would have to turn on the ignition then press your button to activate the fuel pump before you could start the car.


So I could even hook up the kill switch to whatever is turned on when the unlock button on my key fob is pressed(interior lights come on). Then when I get in the car I can press the kill switch, put the key in and start the motor.

Thanks! This is just what I was looking for.



So I could even hook up the kill switch to whatever is turned on when the unlock button on my key fob is pressed(interior lights come on). Then when I get in the car I can press the kill switch, put the key in and start the motor.You mean have your pushbutton get power from the courtesy lights so that you could only activate the fuel system when they were on (such as right after getting in the car)? Yes, you could do that but it might have undesirable consequences. For example, if you were sitting in your car waiting for someone, you would have to open the door (or do something else to make the courtesy lights come on) before pressing the kill button in order to start the car.

You mean have your pushbutton get power from the courtesy lights so that you could only activate the fuel system when they were on (such as right after getting in the car)? Yes, you could do that but it might have undesirable consequences. For example, if you were sitting in your car waiting for someone, you would have to open the door (or do something else to make the courtesy lights come on) before pressing the kill button in order to start the car.


Good thinking, ill just wire up the kill switch in parallel with courtesy lights and ignigtion on :)

Newbie question...why? I apologize for my ignorance. lol

Newbie question...why? I apologize for my ignorance. lol

This is to make the car harder to steal. If the fuel pump isnt working you wont be able to drive the car. The more common starter kill switches can be defeated by shorting the starter and maybe even rolling the car and popping the clutch.

the wire and relay for the fuel pump is by yourt left foot under the door trim panel...put a on off switch in the ground for the relay


Which wire is it? There are two orange 14 or 12 guage wires that run to the back of the car along the drivers seat. I used my wire finder hooked up to the fuel pump relay and it seems to be these wires, but my diagram says it should be grey.

You want to interrupt the fuel pump power on the coil (low voltage) side of the fuel pump relay not on the actual fuel pump power wire. It's safer and it's also easier to fix should your relay fail for some reason. You can put it in the relay coil power wire (dark green with white) or on the ground side (black with white). The power side will be easier because you can get it at the PCM and run through the grommet below the PCM into the car for your switch. The dark green with white wire is in position 9 of the red connector on the PCM.

If you really want to use the fuel pump power lead, the easiest place to get it is at the large 48-pin inline connector under the dash to the left of the steering column. It's the gray wire along the outside edge between a dark green wire and a black wire. There is another gray wire on the opposite edge of the connector but it doesn't have any wires beside it.

You want to interrupt the fuel pump power on the coil (low voltage) side of the fuel pump relay not on the actual fuel pump power wire. It's safer and it's also easier to fix should your relay fail for some reason. You can put it in the relay coil power wire (dark green with white) or on the ground side (black with white). The power side will be easier because you can get it at the PCM and run through the grommet below the PCM into the car for your switch. The dark green with white wire is in position 9 of the red connector on the PCM.

If you really want to use the fuel pump power lead, the easiest place to get it is at the large 48-pin inline connector under the dash to the left of the steering column. It's the gray wire along the outside edge between a dark green wire and a black wire. There is another gray wire on the opposite edge of the connector but it doesn't have any wires beside it.

Okay, im going to use the dark green with white wire on the relay coil side.

Now I just need to find an ignition on wire(ie something that is powered when you turn the ignition to on). Where is one under the dash near the pedals? Also, how do you know where all these wire are???

Okay, im going to use the dark green with white wire on the relay coil side.

Now I just need to find an ignition on wire(ie something that is powered when you turn the ignition to on). Where is one under the dash near the pedals? Also, how do you know where all these wire are???Ancient Chinese secret...I could tell you but then I'd have to kill you :jest:. (Actually, it's in the service manual.)

There are numerous ignition controlled wires at the steering column but the best place to get power for accessories, etc. is one of the three special ports in the fuse panel provided for that purpose. They are single blade ports labeled BATT (constant battery power), IGN (ignition controlled power), and ACCY (ignition and RAP controlled power). They are each 15-amp circuits so be sure to add an inline fuse if that's too muchfor your wiring.

Ancient Chinese secret...I could tell you but then I'd have to kill you :jest:. (Actually, it's in the service manual.)

There are numerous ignition controlled wires at the steering column but the best place to get power for accessories, etc. is one of the three special ports in the fuse panel provided for that purpose. They are single blade ports labeled BATT (constant battery power), IGN (ignition controlled power), and ACCY (ignition and RAP controlled power). They are each 15-amp circuits so be sure to add an inline fuse if that's too muchfor your wiring.

Damn I need to get a service manual. Thanks so much for all the help. I had to button up my car so I will finish this later, im not done with you yet :jest:

I had the latching relay working on the bench but in the car the fuel pump wire wasnt enough to keep the relay open. I guess I need to wire the ign on across the relay as well.

I installed a valet switch(actually just quick disconnects) so I am leaving that connected in the meantime.

http://img2.putfile.com/thumb/5/14721303245.jpg (http://www.putfile.com/pic.php?img=5556569)

Okay I made a diagram of what I did and what I plan to do. The red parts(click image to see them better) are what I plan to do, will it work? Im skeptical. Maybe I should use a different relay so it doesnt take as much to keep it open? Im using a 30amp auto relay currently. Or maybe 2 relays.

Also, should I use fuses, what kind and where? I dont want to fry my pcm.

bump :drive:

Sorry...missed your earlier post. Give me a little while to look at it and perhaps come up with a schematic. I'm not usually on here on weekends so it might be Monday.

I'm a little concerned about connecting an ignition power source to the fuel pump control wire from the PCM. What about using two relays? Wire the first as a latching relay like in the diagram but with ignition controlled power output to be used as the coil supply of the second relay. Then you can just use the second relay 30/87 terminals as a simple cutoff for the fuel pump relay control wire.

Ill use two relays. Thanks, will post up results.

I should finish this up in the next few days. I have one of those gold colored fuse box pins which im going to stick into the IGN fuse slot. Then I will solder a wire to it and then too the relay, the other side of the coil will be grounded.

Ive had trouble soldering to the relays pins(they are a dull gold color), should I use quick connects with wires instead?

Quick connects (i.e. spade terminals) will work fine. In fact, they may be preferable in case you ever need to replace the relay - they are electro-mechanical devices that don't last forever. If you really want a professional looking job, many electronics supply stores sell relay pigtails that have all five wires with terminals in a (semi-) protective plug.

Had a big scare. I got it wired up and when I tried it I heard something fry and afterwards my gauges didnt work. I thought I fried my pcm but I only blew the gauge fuse which happens to be right above where I tapped into in the fuse panel.

Here is exactly how I wired it up, I didnt use any fuses. Where should I use them? Why did the gauge fuse blow?

My switch is only rated at 3amps. The valet switch was closed when I did this.

ps after I get this working ill do a write up so all your help isnt wasted on me :jest:

http://i178.photobucket.com/albums/w259/NoTickets/kill-switch-diagram-2-relay.jpg

white bird helped me wire my kill switch about a year ago (through PMs). he's very knowledgeable. still works like a charm. a write up would be great, as i wasn't able to find a lot in our archives hence, the PMs to white bird.

You've got the ignition power going to the wrong terminal of the latching relay - it should go to the same terminal as the diode. The idea is that power first comes through the momentary switch to pin 85 to trip the relay. Then power is available on pin 87 (from pin 30 because the relay is closed) and it flows through the diode to pin 85 keeping the relay tripped even though you release the momentary switch.

I got it working. Like you said I switched the 86 to be a ground and put IGN on 85 behind the switch. I cant thank you enough.