Correct way to wire battery cutoff switch.

Posted by project_tsi, Jul 23, 2006
Bolt-on Tech - 4G63 intake, exhaust, intake manifold, ignition, fuel system, cooling, etc.

  1. project_tsi

    project_tsi DSM Wiseman

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    Eau Claire, Michigan
    I'm wondering what is the correct way to hook up this kill switch. I mounted the batt in the rear and I can't come up with a solid answer. The instruction sheet that came with the switch states to run the switch with the engine/body ground, but I believe I read that NHRA rules require it to be in the positive cable. I don't know for sure and need a answer.

    Help me out and any other good tips would be appreciated, like is another cable needed to feed the alt to the battery directly or is just the one cable fine?

    Thanks all.
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  2. GVR4592

    GVR4592 Proven Member

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    From the NHRA rulebook:

    You also have to wire the alternator directly to the battery to make everything work properly.
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  3. project_tsi

    project_tsi DSM Wiseman

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    Eau Claire, Michigan
    Thank you for the NHRA info. What is the correct way to wire the fuse inline with the batt and switch? Does it go Battery-fuse-switch-to engine, or Battery-switch-fuse-to engine?
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  4. MXD

    MXD Proven Member

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    Battery-fuse-switch-engine. You want the fuse no more than 18 inches from the battery positive
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  5. DSM90AWD

    DSM90AWD DSM Wiseman

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    Bear, Delaware
    Dan, be sure to take plenty of pics of the install so I can copy you :)
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  6. project_tsi

    project_tsi DSM Wiseman

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    Eau Claire, Michigan
    Ok well what is the exact correct way to run the wire from the alt? Does it go directly to the batt, or to one of the posts on the switch, or what? And what size inline fuse? I thought it would have to be ran to the switch to cut power to the alt, if not, the car would still run since the alt can run the car by itself.

    OH heres a few pics so far. Let me know if anything looks wrong. I will be adding a box, just not right now.

    Attached Files:

    #6
  7. Ludachris

    Ludachris Founder & Zookeeper

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    Roseville, California
    Dan, I believe you're going to need a box too.
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  8. Ludachris

    Ludachris Founder & Zookeeper

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    Roseville, California
    I actually went with a 200amp circuit breaker. It's wired from the Battery > Switch > Breaker > Fuseblock under the hood > Starter/Accessories.

    I haven't yet wired the Alternator shutoff switch from Painless that I bought a while back. I'm lazy and didn't feel like running another set of wires through the car. But, when I last went the drag strip, the car shut off completely with just the batter switch - the alternator didn't keep the car running.

    One word of advice - try to modify your mounting bolts for the battery so that you can swap the battery by yourself. I used to have mine setup the way you do and had a hell of a time changing out a battery. It's tough to get it bolted down with one person with the bolts hanging free.
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  9. 92awddsm

    92awddsm DSM Wiseman

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    Chesterfield, Virginia
    You run the positive cable to the switch, not the negative.

    To be nhra "legal", first, you need to mount the battery in a sealed box that has a vent exiting the outside of the car. You also need to run the altenator charge wire to the battery side of the switch or directly to the positive terminal of the battery. When wired properly, the car should turn off when the switch is turned off. If the alternator is feeding between the switch and the engine, it will still run even if the switch is turned off. You also need to clearly label the switch "on" and "off" or it wont pass tech.

    As far as the fuse, I run a 100 amp fuse on the engine side of the switch and then another 100 amp fuse under the hood. The most important fuse would be the underhood fuse and the other at the switch is just insurance in case the cable grounds out somewhere between the underhood fuse and shutoff switch. If you need any more info, let me know. I would snap a couple of pics for you but my car is currently nowhere near me right now.

    And one more thing, I actually ran a new 8 gauge wire directly from the charge terminal of the alternator, through an 80 amp fuse, and then to the battery side of the shutoff switch.

    edit: the battery also need to be secured by 2- 3/8" minimum bolts(or allthread) through the framerail. By the looks of the picture, I assume that is what you did.
    #9
  10. 99gst_racer

    99gst_racer Moderator

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    Coloma, Michigan
    Chris, any chance you still have that Painless part number?
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  11. project_tsi

    project_tsi DSM Wiseman

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    Eau Claire, Michigan
    It is.

    I am going to add a box like my previous post stated, I just didn't want to do it right now. The on/off is also clearly labeled.

    Yes it is. I have 4 bolts holding the base down.
    #11
  12. AWDDSMCRAZY

    AWDDSMCRAZY Proven Member

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    In this picture I'm assuming the switch is wired after the fuse or breaker? The positive that close to ground freaks me out. Ever since my buddy wired up his stereo with the fuse closer to the amps, and it caught fire I always mount all fuses out of battery before they go anywhere.

    [​IMG]
    #12
  13. project_tsi

    project_tsi DSM Wiseman

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    The setup goes battery-fuse-switch-to engine bay. Take a look at my first pic, the little black box about 6" after the cable, holds the fuse, which then goes around the back into the switch, out the switch into the engine bay. I don't see how the ground being attached there presents any type of problem.
    #13
  14. 99gst_racer

    99gst_racer Moderator

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    Coloma, Michigan
    Ouch. Big mistake. Your fuse/breaker should ALWAYS be within 18" of the positive terminal on the battery.
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  15. Ludachris

    Ludachris Founder & Zookeeper

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    Roseville, California
    Sorry for just seeing this Paul - the part # of the kit I got is 50105. I believe I got it from Summit.
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  16. 99gst_racer

    99gst_racer Moderator

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    Coloma, Michigan
    Thanks for the part number, Chris. Man, that's an expensive little bugger, eh.
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  17. 95GSXracer

    95GSXracer DSM Wiseman

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    What I did on the 2g was use the flaming river switch with extra NC/NO contacts. Since the pump is right there at the back of the car, I ran the pump rewire through the NC contacts. Hitting the switch cut the main power cable and the pump, killing the motor. No assing around with the alternator. It did take 2-3 seconds for the motor to shut off, but it passed tech every time they tested it, and my local track is very strict on the rules. One more option anyway...
    #17
  18. DSM90AWD

    DSM90AWD DSM Wiseman

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    Bear, Delaware
    Since the re-wired fuel pump's (+) feed is directly off the battery anyway, couldn't you simply wire it from the same downstream lug on the cutoff as the (+) line leading to the engine compartment (fused of course)?

    Has anyone run one of the remote-rod setups from Summit/Flaming River? Seems like a nice option to be able to remove the external On/Off switch when not at the track so as to remain "stealth" and not attract attention from coppers/thieves ;) :dsm:
    #18
  19. 92awddsm

    92awddsm DSM Wiseman

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    Chesterfield, Virginia
    Do you mean like this?

    Its not very noticable from the rear so I dont worry about it. And I am using the flaming river switch and the rod was cut down to 7" if I remember correctly.

    Attached Files:

    #19
  20. elfroggo

    elfroggo Proven Member

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    This borders off topic I suppose but why don't more people think of a lightweight battery installed in stock location instead?

    For example:
    http://www.brailleauto.com/ProductCart/pc/viewCat_h.asp?idCategory=4

    If you are doing it for weight relocation, well you still are using a full size battery, heavy cable routed to the back of the car and you need a battery box to keep it legal.

    The only real downside is of course that they aren't as durable, more expensive, powerful etc.
    #20
  21. DSM90AWD

    DSM90AWD DSM Wiseman

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    Bear, Delaware
    Looks nice! Do you have an inside pic? Was wonderign where you'd mounted the cutoff.


    I relocated mine for a few reasons (in order of my importance):

    1.) Less clutter in the engine bay = cleaner and easier to service
    2.) Less chance of grounding battery to tools (arc-welded several box wrenches to date :coy: ) and zero chance of the battery grounding to the strut bar/hood.
    3.) DSM Battery is already too small (last me only a couple years) so didn't want to go smaller.
    4.) Better weight distribution

    I agree, it's a much bigger hassle to do the whole battery relocation since you need a $100 NHRA-certified sealed battery box, $50-100 wiring kit and a $40-80 cutoff swich to be "NHRA legal", though since I had to do something with my SMIM anyway, figured the extra cost was worth it (to me anyway) :D .
    #21
  22. 92awddsm

    92awddsm DSM Wiseman

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    I can get you a pic tomorrow. Its a little dark here right now.
    #22
  23. fourreGsixty3

    fourreGsixty3 Proven Member

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    A big reasone to do it is because the SMIMs sit so low, that the battery must be moved to fit the UICP...unless you have a custom done TB elbow that goes a little bit past the battery then connects to the UICP. Also I took out my battery, the bracket holding it up, a/c, p/s, and the charcoal canistor for gas vapors all out and it looks super clean in my engine bay...well not now since I pulled the engine, and tranny, then had to drop it back in before I leave for Boston, and now wires are just all over, but it DID look super clean in there. I see your new GSX is a teal color similar to mine Dan, nice:)

    Dustin
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  24. project_tsi

    project_tsi DSM Wiseman

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    Actually guys I never updated the thread b/c I had a change of mind. I decided to keep it in the stock location, yet lower.

    [​IMG]
    [​IMG]
    #24
  25. fourreGsixty3

    fourreGsixty3 Proven Member

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    Sexy engine bay Dan.

    Dustin
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