Hooking up kill switch on "08 FX Nytro MTX

[bholmlate]

Has anyone ever hooked up a tethered kill switch or have any knowledge of how to hook one up. After seeing a runaway sled with a stuck throttle on a vidoe I decided to hook one up. It gave a whole new meaning to a weapon of mass distruction.
I found one that works with a keyed ignition system and the instructions say to splice into the wire running from the run/stop switch to the ECU.
After a little investigation I discovered that there is a brown and a brown/white wire running from the run/stop switch. However both eventually make their way back to the ECU. This tells me that both would work. However one run has a directional diode in it. This tells me that the pwoer flows in a certain direction through the system. This also tells me that one wire would be better to splice into then the other one. Not knowing the direction inwhich the power is flowing, I am not sure which of the two wires would work better. Any Ideas??????

If anyone has any extra snow they would like to get rid of please pass it along We are still looking at dirt and roicks in Reno Nevada.

 

[Len Todd]

We have a little extra snow. But, you going to have to come and pick it up.

I will look into this a bit later tonight. I am teaching at the local University right now and the studets might not like me digging in to the E-Schematic of your sled right now. But, have you considered installing the tether switch in series with the key switch?

 

[bholmlate]

Hey Len T.

Thanks for th reply. No i have not though of that. Could you explain what you exactly mean by paralleling the key switch? I think I understand what you are talking about but i want to make sure. I am a little like a fisn out of water here at the moment.

I will ask me brother, head mechanic, on the sled about this =).

 

[Len Todd]

I used the wrong words (paralleling) in the above post and corrected the post above, just now. Students started walking in on me, mid-thought. But, ...

If this was me. I would install the tether switch in the power circuit controlled by the key. This would positively shut all power off, if the tether was pulled. It is a very positive cut off. (Verses, tapping into a circuit that is an input to the CPU and expecting the CPU to read that input and then shut off the sled.)

It just seems to me that putting the tether switch in the power circuit makes it more "fail safe." Question is, how "fail safe" do you want it. And if you are racing, what is really required.

So, ... Assuming you have a tether switch that can be configured to go open on a tether pull, where do you put the switch? : There is a red wire from the battery to the Main Fuse. (There is a larger red wire branching off that circuit for the Starter Motor and a couple relays. This is NOT the wire you want to install the switch in.) You could put the switch in the Red wire to the Main Fuse. There is a Red wire continuing on from the Main Fuse to the ignition fuse. This may be the easiest to access. You could put it in there. There is a red/yellow wire from the Ignition Fuse to the Key Switch. You could put it in there, but you are now not getting the whole sled de-powered on a tether pull. But it would still work. In either of these locations, you are before the key switch. Once you get to that switch, the power is distributed a lot. So getting what you are after is more difficult.

But, as you suggested, if you installed the tether switch in the brown wire between the Kill Switch and the Key Switch, you could still get an engine kill. It's the brown wire w/o the diode. The diode just keeps the Load Control Relay from chattering.

 

[bholmlate]

Hey Len T.

Thank you very much for the information. Your explaination clears things up. That is what I thought you were refering to in your first post. I just wanted to make sure I was on the same page =) I dont race so putting a kill switch on is more for my peace of mind then anything.

Thank you very much for the great Idea. Hooking it up the way you are suggesting would definitly be a more psotive cut-off. I never would have thought about going in that direction.

I also put a call into my local dealer who told me that it really doesn't matter too much which of the wires, running from the run/stop switch, you splice into. He said that all you are doing is opening the circuit which interupts the power the same way the run/stop switch does. However i think i am going to look into what it will take to do it your way because of the reason you mention.

Thank you again

 

[bholmlate]

While reading another posting in the Nytro MTX section I found out that on The Ulmer Racing web site under instructruction. They have written instructions on how to install a Kill switch on an Apex and Nytro along with pictures for anyone interested in installing a kill switch.

 

[Len Todd]

That is good to know. Thanks for the tip.

Click Here for a link to Allen's Tether Instructions.

Also, I see it is a bit different for the Apex (i.e. you are limited to the Brown/White wire.)