1 Topic by Scubandreams (edited by Scubandreams 2020-10-10 02:57 PM)

  • Registered: 2018-02-24
  • Posts: 8

Topic: Need help with Kill Switch

Ok folks, feel free to flame but I need some help with a kill switch with a car that is unfamiliar to me.

Car - 1984 Nissan 300zx; assume nothing is original … except for the ignition maybe.  Engine is from a Nissan Xterra I believe.  If this was on our camaro that is a "two wire" car I would have this solved already...

Anyways...

- Kill Switch in the off position - Car will not start / accessories /dash etc will not have power.
- Kill Switch in On position - Car starts

Car Running:

- Kill Switch in off position, car remains running.

Here is the picture of the back of the kill switch and a "high tech" schematic I put together. in the same orientation

https://i.imgur.com/uM6naFj.jpg
https://i.imgur.com/P9cqTF3.png

Trouble shooting to date: We removed the "mystery" wire, and the car will not start nor will the accessories (dash board lights etc) turn on when key is turned to ON/START in ignition.  This makes me believe its the main power for the ignition...however I am unable to trace it as it gets lost in a rats nest of wires.

The wire on the battery side that goes into the RL-44 relay has three additional wires that go into/are connected to said relay - unable to trace.  I am not sure Which exact switch this is, but a similar one calls for a ignition in/ out on the spades … any idea what switch I have?  If I do need an ignition in/out where do I find this wire and how does it relate to the ignition 12v that I think is already wired to the starter solenoid side?

Any help would be appreciated, I can turn a wrench but this electrical stuff makes me go crazy.  Thanks.

  • From: Tustin, CA
  • Registered: 2010-12-30
  • Posts: 3,275

Re: Need help with Kill Switch

I dont know what an RL44 relay is but I would guess that something on the battery side of the switch is continuing to feed the ecu/fuel pump.  In general you are looking to isolate the battery and alternator output on one side if the switch and everything else on the other.  Its possible the alternator output can be dumped into one of those terminals but I'm unfamiliar with that kill switch.  If you move all that stuff besides the battery to the other side of the switch, I would guess you'd be ok.  Then figure out where the alternator output is going and make sure its going somewhere that doesn't harm itself.

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  • From: Elverson, PA
  • Registered: 2017-08-15
  • Posts: 1,127

Re: Need help with Kill Switch

Where's the alternator wire connected in your set-up?

Alternatively, having done software and hardware support in the past, there comes a time to start fresh, with new equipment.

Or trace and label the rat's nest.

The Lemons store has a kill switch:

http://store.24hoursoflemons.com/produc … switch.htm

and the resource includes a wiring diagram for guidance.

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  • From: CT
  • Registered: 2016-08-09
  • Posts: 130

Re: Need help with Kill Switch

I agree, I think your 'mystery wire' is the feed to the ignition/ecu, etc., so when you remove it, the engine will start.

I think you mean that the large red wire is connected to the starter motor (not the solenoid).

You don't indicate where the alternetor is connected in all this, but I would guess that its connected to the large diameter wire on the right (with red tape). So, even if you open the kill switch, I'm guessing that the alternator is still connected to the ignition circuit and you are powering the car that way. That explains the behavior you observed. Disconnecting the battery will NOT stop the car. You must also disconnect power to the ignition system (or ecu, or fuel pump relay, etc).

The key thing here is that there are 3 switches in the kill switch, 2 of them operate in the same manner, and the third switch has the opposite functionality. You are only using 1 of the 3 switches.

There are several things wrong with this setuip (I'm making some assumptions about the functionality of switch "1" and switch "2"):

- The ignition circuit, or the ecu, or the fuel pump relay (ideally all of them) should be wired through switch "2". So when the main switch opens, switch "2" also opens, cutting power to the things that make the car run.

- Your 'jumper wire' is correct, but there should be a resistor from the other "1" terminal to ground. That will give the alternator a path to dissapate any residual voltage when the main switch is opened. Sometimes alternators can be damaged when you remove the battery and there is no other load on the alternator.

- You have some items (wipers, lights, fan switch, RL-44 relay) that ALWAYS HAVE POWER APPLIED! This defeats the purpose of the kill switch. The only thing that should be connected to the 'upstream' side of the main switch is the battery positive. This ensures that when the kill switch is opened, that there is NO POWER applied to anything - especially things under the hood where you might have a fuel leak, etc.

Check out this thread from a few months ago. I included a few diagrams to try to provide some details on how to hook it all up.

https://forums.24hoursoflemons.com/view … p?id=39190

What is the brand of the switch? We have one of these, where the smaller switches are labeled "Z" and "W". Your's are labeled "1" and "2", but should serve the same purpose.

https://www.pegasusautoracing.com/docum … =TECH00109

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  • Registered: 2018-02-24
  • Posts: 8

Re: Need help with Kill Switch

Ok - thanks, this gets me things to test/do/think about.  Will report back .

  • Registered: 2018-02-24
  • Posts: 8

Re: Need help with Kill Switch

Ok here is where I am at.

I moved all the extraneous BS onto the same side as the Mystery Cable and the Starter Cable - no change in status.  Tried to trace the mystery cable it ends up somewhere near the fuse box, we think (literally, out the firewall...one square around the car (front to back and passenger side to drivers side).

So, here is where I am at...or thinking about doing.  We started the car and then pulled the ign/engine control (assuming its the ecm) fuse and the car died.  So, i'll just wire that onto the 6-post switch ,,,

I am sure I am about to blow up something by doing so, so feel free to stop me smile

7 Reply by Guildenstern (edited by Guildenstern 2020-10-11 05:19 PM)

  • From: Cleveland, OH
  • Registered: 2011-09-03
  • Posts: 2,227

Re: Need help with Kill Switch

Just re wire it correctly, Fudging here will only bite you in the ASS.

EVERYTHING must be OFF when you hit the OFF switch.

This isn't an ignition switch, it's a KILL switch.

Find which smaller terminal set is "closed on OFF" then wire it as diagramed through the pegasus link.

Only the Battery + should be on the pre-switched side, that jumper wire is suspect As Hell.

Always approach a used car with the assumption that the previous owner had no clue what they were doing. Then fix it properly.

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  • From: Tustin, CA
  • Registered: 2010-12-30
  • Posts: 3,275

Re: Need help with Kill Switch

Sounds like the alternator is still feeding into the ignition side of the switch.  Need to find that wire and get it off that side.  Or just the wire that energizes the alternator.

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Re: Need help with Kill Switch

Scubandreams wrote:

Ok here is where I am at.

I moved all the extraneous BS onto the same side as the Mystery Cable and the Starter Cable - no change in status.

That just means that none of the things you moved are involved in keeping the car running. Based on your description of those items, I wouldn't expect any change in behavior of the kill switch. What you have done is important, though, as you have now allowed the kill switch to completely isolate/disconnect the battery from all vehicle systems.


Scubandreams wrote:

We started the car and then pulled the ign/engine control (assuming its the ecm) fuse and the car died.  So, i'll just wire that onto the 6-post switch

Agree. You need to find the wire that runs through that fuse, and wire it across the kill switch - whichever of the small set of terminals is configured to OPEN when the kill switch is turned to the OFF position. That will stop the car. It can't be said enough times "DISCONNECTING THE BATTERY WILL NOT STOP THE CAR". Once the car is started, the battery isn't doing anything. When running, the alternator is supplying all the power for the vehicle systems, including the ignition, wipers, gauges, etc, and it is also keeping the battery charged.

The 'jumper' wire is fine where it is (assuming that your switch "1" is the same my switch "W"), but its not doing anything at the moment, because there is no resistor on the other terminal. Again, see the post. Again, check out this post: https://forums.24hoursoflemons.com/view … 53#p337653 for more wiring details.

The terminals on my switch are labeled "Z" and "W". Yours are labeled "1" and "2". You need to figure out which one is which - they act in opposition to each other - they are never in the same state at the same time. When the main switch is open, one of them will also be open, the other will be closed.

Any idea what brand the switch is?

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  • From: NH
  • Registered: 2010-01-20
  • Posts: 3,299

Re: Need help with Kill Switch

Echoing what others said above. Wire the thing correctly. Start by removing the kill switch entirely, figure out what the heck is going on, and make it work like stock. Then go and wire it back in the right way.

There are many brands of that style switch, but they all work the same.
The two large posts are there to attach cables that run from your battery + post and then to everything else in the car. There should be nothing else connected on the battery side, nothing. Just a cable going to the + post.

The smaller terminals on the bottom will work opposite each other. One pair (I would guess the ones labeled "1" on yours) will work the same as the large posts. They will be connected when the switch is on, and disconnected when the switch is off. Use a multimeter to confirm. The other pair (Again, guessing the "2" posts on yours) will be disconnected when the switch is on, and connected when off.

The point of these is to use the first pair (that work the same as the large posts) to interrupt something that kills the engine. Could be an ignition wire, ECU power, whatever, just has to be something that makes the engine immediately stop. The other pair (guessing "2") is for you to connect the main car power post switch to, and then a large power resistor to ground. You can literally just jumper the large post that is on the car side (NOT the battery side) right to one of these terminals, and then attach the resistor and ground to the other.

If you do the above, when the switch is on, the car should perform like normal. When you flip it off, the car should shut off, and then there should be no power to anything in the car at all. Nothing. No radio, no fuel pump, no lights, no auxiliary power ports. Not even your radio should have power if you run a battery eliminator.

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