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j12piprius 11-07-2014 04:11 PM

kill switch relay ~ with led indicator light
Let me know if this is right setup for a kill switch, to kill the injectors when EOC,
and for an led indicator light that goes on when the injectors are off.

My plan is to use an SPDT 5 pin 40 amp NC relay, i.e. normally closed (on).
The relay has two circuits, a control circuit coil, which controls the load circuit switch.

control circuit
85 ~ is powered by positive battery wire, which can not be from 30;
86 ~ goes to the kill switch, which can be anywhere in the 85~86 circuit, then to ground.

load circuit
87 ~ positive to led light, to 87, connects to 30 when relay is on;
87a ~ positive injector wire, to 87a, connects to 30 when relay is off;
30 ~ goes through negative injector ground wire whether relay is on or off.

The same positive (not from 30) can piggyback to 85 and 87.
The 30 and 86 grounds can (maybe) piggyback to the injector ground wire.
The idea is for the kill switch to turn off the injectors, which turns on the relay and led light.

2000mc 11-07-2014 07:36 PM

You would want the injector feed on 87a, and the indicator on 87
Edit, missed you using a nc switch, so never mind... I did mine with a normally open switch, so the relay isn't always powered on

Baltothewolf 11-07-2014 09:25 PM

Put the hot side of your injectors onto pin #30 along with a jumper wire (consult my thread to see how I did it) to #85. Then run the cold side of the injector to pin #87A. After that, run your ground from 86 to your kill switch, then out to whatever ground you want to use. Put your LED on pin #87 and it should work when you hit the switch, because the power that would normally be going to the injectors, is now going to the LED, no?

j12piprius 12-05-2014 01:05 AM

reversing the connections
It occurs to me that the positive injector wire at 30, going through the led light (or coil) then to ground, would turn the injectors back on. I'm going to avoid that by turning them around, running a positive wire through the led to 87, for when the relay is on, the injector positive to 87a for when the relay is off, and run the ground through 30 in reverse.

cowmeat 12-05-2014 08:02 AM

You all need to get this worked out before I do mine this weekend, lol!

I'm going to get a momentary switch with an "angel eye" red halo light around it for the injector kill switch, and I may get a green one to replace the black brake regen button, but I need to know how to hook them up.

My kid's going to give me a big piece of heat shrink to make it all look legit, so it should look pretty good when I'm all done with it.

j12piprius 12-05-2014 12:40 PM

positive wires
I'm sure this will work. :)
What I'm wondering is where to find an easy to use positive connection in the dash.
Maybe I can splice into the one for the radio, but would rather not have to take the dash apart.

2000mc 12-05-2014 01:36 PM

Why string a power wire to the led and switch? Setting up switches and indicators on the ground side lets you make a ground wherever it's convenient, and makes an added on wire that shorts to ground less impactful

j12piprius 12-05-2014 07:29 PM

a power wire to the led and switch

Originally Posted by 2000mc (Post 458372)
Why string a power wire to the led and switch? Setting up switches and indicators on the ground side lets you make a ground wherever it's convenient, and makes an added on wire that shorts to ground less impactful

Using a NO switch, as you suggested in post #2, the relay is off when the injectors are on. The injector positive can't power the led and switch, because that would keep the injectors on, instead of turning them off. I'm not sure what you mean by the ground side, as the load circuit can be used in either direction.

2000mc 12-05-2014 08:22 PM

My thought was to run the positive(pgm-fi?) to 30 and 86. 87a on to the injectors. 85 to your NO switch, other side of the switch to ground. 87 to led, other side of led to ground.

Is there a conflict with the wiring / inaccessibility with something that would make that not work or difficult? I usually find it harder to find an extra power wire, unless I've done it before on the same model

j12piprius 12-05-2014 08:41 PM

Wouldn't powering 86 and 30 from the positive injector wire keep the injectors on when the relay was turned on, both from the current through the control circuit coil, and the current through the led light? Perhaps I'm not clear on which side of the injector wire is positive, and which side continues to ground.

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