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S14 kill switch wiring diagram?

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  • S14 kill switch wiring diagram?

    I need to install a kill switch in the S14 for it to pass tech on race weekends. I am actually going to install 2 kill switches in one loop (one inside the car and one outside).

    I have done a LOT of searching and am getting a bit confused. I keep finding threads about guys who are installing what is basically an anti-theft immobilizer switch. That's not what I need. I need everything shut down immediately on the turned switch.

    I am using 4 pole switches to break two different circuits, and know that one of the circuits will need to be the (+) wire coming off the battery.

    For the other circuit, I have heard that I can interrupt the ignition circuit. I am not sure which wire I need to use to do this. I am open to breaking a different circuit, if it works, but would like to use a wire from the ignition or ECU as those are both readily available as the car sits (stripped).

    Could anyone shed some light on this for me?

  • #2
    I just put a main kill switch in my car. All it has to do is interrupt the battery negative cable. Pretty sure that's how I saw it done on a local Bmw racecar.

    Sent from Skynet
    SM 63 KA-t 470hp 480tq G30-660 A2W IC

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    • #3
      Ya, but I thought that doing that in a 240 wont work as the car's Alternator will keep it running. I therefore thought that you have to break two circuits.

      Your's works like that?

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      • #4
        Oooh, I didn't think about using it to kill the engine at the same time as disconnecting the battery. That would require more thought and I need sleep for exams.

        Sent from Skynet
        SM 63 KA-t 470hp 480tq G30-660 A2W IC

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        • #5
          Buy this kill switch and follow the wiring diagram. Works like a charm in my S13:

          https://www.pegasusautoracing.com/pd...structions.pdf

          edit: sorry, didn't see that you were looking for a particular wire. I believe I interrupted a black/red wire coming off the ignition switch that runs to the ignition coil relay. Browse the S14 FSM wiring diagrams.
          Last edited by gills; 04-23-2014, 09:23 AM.
          Core4 Motorsports
          CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
          S14 VQ AER Endurance Racing Team

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          • #6
            Ok, well that makes sense. After looking at some diagrams that black/red wire is the On power to the coils. I will try this and see how it works. Thanks!

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            • #7
              I used a regular 2-pole switch in my car..

              pole 1: battery, starter, alternator.
              Pole 2: engine bay fuse box.

              I ran 4awg from the battery to pole 1. 4awg from pole 1 to the starter (so the starter is always hot and you're not trying to switch the high starting current. makes the contacts on the switch last longer that way.
              Also pulled the wire from the alternator off the fuse box and ran a new one to pole 1 of the switch. This takes all power fed into the system and puts it on the same side of the post. The other benefit to this is that the alternator always has a battery load on it so the thing can't "freewheel" when you shut off power. Freewheeling will kill the diodes in the alternator if there's not a load on the alt and the field coils are still energized.

              Then I ran an 8awg wire from pole 2 of the switch to the engine bay fuse box. this is where the factory lead from the battery goes. cut off power to this, and it kills everything under the hood EXCEPT the starter. But since there's no power to the ignition switch or ECU to activate the starter solenoid, the engine won't crank either. Everyone is happy, alternator is safe, 100% effective shut-off when the switch is tripped.
              Originally posted by SoSideways
              I don't care what color they are as long as they are LONG AND HARD.
              '04 G35 Sedan 6MT- The DD
              '96 240SX- The Track Toy

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              • #8
                I'm doing a 1JZ S13 for a friend right now and I used the Pegasus switch. I'm doing it just like the diagram. I went around and around on the best way to do this, since I'm wiring the whole car. This makes the most sense.

                Originally posted by Matt93SE View Post
                I used a regular 2-pole switch in my car..

                pole 1: battery, starter, alternator.
                Pole 2: engine bay fuse box.
                I did think through this iteration. It will shut the car down, but the problem here is that you still have cables in the engine bay with 12V on them. Even with the switch thrown, the heavy cable to the starter and the medium cable to the alternator still have power, and they are probably unfused as well. In the event of a crash, which is why you would have a cutoff switch to begin with, if you have a fire started by arcing these wires, it will continue to arc even after the safety guys flip your switch.
                She's built like a Steakhouse, but she handles like a Bistro.

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                • #9
                  How would you wire that Pegasus switch on an SR? Have it go to the ignitor chip?

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                  • #10
                    Originally posted by Vlad View Post
                    How would you wire that Pegasus switch on an SR? Have it go to the ignitor chip?
                    The ignitor doesn't have power running to it. The "Z" section of that Pegasus switch should just interrupt the power to the coil pack harness.
                    She's built like a Steakhouse, but she handles like a Bistro.

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                    • #11
                      Originally posted by Epstein View Post
                      I did think through this iteration. It will shut the car down, but the problem here is that you still have cables in the engine bay with 12V on them. Even with the switch thrown, the heavy cable to the starter and the medium cable to the alternator still have power, and they are probably unfused as well. In the event of a crash, which is why you would have a cutoff switch to begin with, if you have a fire started by arcing these wires, it will continue to arc even after the safety guys flip your switch.
                      By the time that happens, there will be much bigger issues to worry about than an arcing battery.

                      This setup has been looked at and approved by SCCA, Lemons and Chumpcar tech inspections so far on several different cars. The main issue is that the car shuts down when you flip the switch. they don't care much past that, and adding a multi-pole switch only adds complication and failure points. I've seen several cars not start on raceday due to these multi-poke switches failing. only once have I seen a 2-pole switch fail, and that one was opened and reclosed a few times while the car was cranking, so I'm sure they arced the crap out of the contacts and ruined them.

                      YMMV.
                      Originally posted by SoSideways
                      I don't care what color they are as long as they are LONG AND HARD.
                      '04 G35 Sedan 6MT- The DD
                      '96 240SX- The Track Toy

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                      • #12
                        FWIW, that 4430 4-pole switch is one of the best and the car where I started racing in LeMons/Chump car has been running with that same switch since 2008 (we're talking a minimum of 4 races per year at 14-16 hours of racing per weekend). Whichever switch you buy, just don't get a cheapo. Every race weekend I go to there always at least one team that has a cheapo kill switch that fails on them and they're running around the paddock like headless chickens looking for a spare.
                        Core4 Motorsports
                        CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
                        S14 VQ AER Endurance Racing Team

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                        • #13
                          Well I got Moroso ones. Don't know if those count as cheap or not. :S

                          As for how to wire them... You guys are saying that I'll have two possible issues? 1) that the switch could fail because it's a 4 pole. 2) flipping the switch could kill the diodes in the alternator.

                          Is that right?

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                          • #14
                            1. The 4-pole switch just has more points to fail, so they tend to fail more often than a 2-pole switch if you assume each set of contacts is good for "1000 switch cycles".

                            2. If you wire it properly, you'll be fine. you can't simply disconnect the alternator feed cables while the car is running and let the alternator "freewheel". That will kill the diodes/voltage regulator in the alternator in short time. The fix for that is to install a resistor in the alternator circuit that gives the alternator a load when you shut it off.. This is why I simply connected my alternator straight to the battery. the car still shuts off when you flip the switch and that's what the SCCA wants. they don't care how it happens, just that the engine and fuel pump immediately stop when you flip the switch.
                            Originally posted by SoSideways
                            I don't care what color they are as long as they are LONG AND HARD.
                            '04 G35 Sedan 6MT- The DD
                            '96 240SX- The Track Toy

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                            • #15
                              A lot of cars are wired alt-to-battery, but you could always put say a 100-120A fuse inline between the kill switch and battery, and run the alt straight to the kill switch ?

                              Then you don't separate the two, which takes care of freewheeling, and you don't have to run too much extra wire, even less if you have the battery in the trunk or cabin...
                              http://responsetype.com/shop/

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