The 24 Hours of Lemons Forums → Lemons Tech → Kill Switch Wiring
Any advice on the kill switch wiring? I've found the pegasus wiring diagram, but I really didn't want to spend $60 on a switch. I saw in another post that the $5 harbor frieght one was common for Lemons. How is that one being wired in? Is the alternator protecting just disregarded?
http://www.pegasusautoracing.com/pdfs/4 … ctions.pdf
If it matters this switch is going in another E30.
Thanks in advance for us that are electrically challenged.
Not to be "that guy" but invoke the search function at the top of the page for plenty of answers to this often asked question.
Personally I'd buy the good switch.
Keep all the power sources & main starter feed on one side of the switch, and everything else (consumers) on the other side of the switch. Most cars will have fat cable running from the Batt to Alt to Starter in some order, doesn't matter how. Leave that alone. Just interrupt anything else that taps into that +12V bus.
This method effectively kills ECU, fuel pump, injectors, ignition, starter solenoid, fans, lights,... without risking any damage to your alternator.
I bought this to put on an '84 e30
If you use a Longacre (or other brand) 4-pole kill switch, the wiring is much simpler than even with the Pegasus switch you linked to above:
http://www.ioportracing.com/Merchant2/m … y_Code=SPS
In short, with the 4-pole switch you can interrupt the main positive battery cable and hook one end of that interrupted cable to one main lug on the kill switch and then the other leg of the cable to the other main lug. Then you can interrupt the wire that goes from your ignition switch to the fuse box and run one leg of that wire to one side of the secondary lugs on the kill switch and the other leg of that wire to the other secondary lug. The 4-lug kill switch thereby kills both the power from the battery and kills the ignition signal, thus telling the engine to turn off and ending the alternator power too.
The linked Longacre switch is $35, not $60. I found it a lot easier to use that switch than try to figure out how to wire in a $5 Harbor Freight 2-pole kill switch, although I know that can be done too. I just haven't ever seen it done and with something like that, I need to see it to know how to do it. Good luck.
I bought the $5 "Made in China" switch from Harbor Frieght and it worked fine til it got rained on one too many times. So I bought the "better" HF switch, it's all metal "Made in India" for $8, so far so good. The handle does not come off like the cheap one so I guess water can't get in it. But I bought a spare $5 back up just in case, cause ya never know........
Mulry,
The Longacre switch you linked is a 2-pole, 4-terminal switch, not a 4-pole. Both poles are NC (normally closed) when the switch is set to "on".
The Pegasus switch Godzilla posted is a 3-pole, 6-terminal switch. 2 poles are NC, one is NO (normally open). The NO pole makes it easy to wire in a dummy load that protects the alternator when the switch is thrown. I don't mean to start an argument over the merit of this, just pointing out the difference.
No objection here, Doug, you're exactly right, I was confusing "pole" with "terminal." Owing to my experience in Lemons coming at this problem a year ago from a decidedly non-racecar-builder background, the Longacre switch was easy to understand, wire in, and it worked to kill the engine, including alternator, as required by Lemons tech. the 3-pole might be better but as I read the instructions, it seems like it might be easier to use if you were building a car from scratch rather than modifying an existing electrical system to work with it. Or maybe I just don't understand the wiring diagram very well. That's entirely possible and actually pretty likely.
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