DIY: Honda FIT Kill Switch
 

###### EDIT ######
Based on my experience and the advice from BaltotheWolf, I don't recommend using the Igniter Fuse method for the Honda FIT. About 15% of the time it causes "dieseling" which prevents the motor from turning off and probably causes damage to the engine over an extended time. I'll update this thread when I have found a new solution for the FIT.
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Just finished my kill switch for my FIT. I don't have a lot of miles on it so I can't say for sure it won't cause trouble, but it uses the ignition coil fuse, which I think is same as key off kill. Anyway, here's how I did it:

Disclaimer: Kill switches are dangerous, I am not an automotive expert, I may have royally f***ed something up with my car, proceed at your own risk.

Parts:
Momentary switch: any, can be low current
Toggle switch: any, can be low current
Relay: Should handle 15A, I used CP1SA-12V-X
Fuse Tap: Got it from Autozone, mini, low profile kind
Wire/solder/connectors: Use what you have

Tools:
Wire Stipper
Crimper
Soldering Iron
Zip Ties

Overview:
Reconfigure Fuse Tap
Wire Fuse Tap to Relay and switches
Locate and remove IG COIL fuse
Install modified fuse tap

Reconfigure Fuse Tap:
The fuse tap is meant to create another circuit in parallel with a given fuse, instead I want it to interrupt the circuit the fuse is protecting (and keep using the fuse for protection) when I cut it with the relay.
http://ecomodder.com/forum/member-ve...2-fuse-tap.jpg

Open the fuse tap carefully with a razor blade, I had to remove the heat shrink off the wire.
http://ecomodder.com/forum/member-ve...sassembled.jpg

Remove and flatten the small fuse blade that is meant for the original circuit. This is hard to do without wrecking it.
http://ecomodder.com/forum/member-ve...-flattened.jpg

Solder a heavy gauge wire to flattened fuse blade and reassemble the fuse tap with the wire sticking out. I had to remove bits of the plastic housing with a razor to get it to close properly. I used super glue to hold it together again.
http://ecomodder.com/forum/member-ve...configured.jpg


Wire Fuse Tap to Relay and Kill Switches:
Now I had the top fuse position on the fuse tap open to accept the ignition coil fuse and two wires that need to be closed for the ignition coil circuit to be closed. I wired them to the Normally Closed taps on my relay so that if anything happened to my kill switch wiring, it would default to closed. Only a catastrophic relay failure should cause this to disrupt normal function of the FIT.
I put a toggle switch and a momentary switch in series so that I can disable to the kill switch if someone else is driving the car or the kill switch button malfunctions and sticks on.
I installed the relay on the fuse bay door and put the toggle switch in one of the extra button slots near the VSA disable button.
http://ecomodder.com/forum/member-ve...-installed.jpg
http://ecomodder.com/forum/member-ve...y-up-close.jpg

Install Modified Fuse Tap:
I removed the IG COIL fuse and put it in the top slot of the modified fuse tap and installed the whole thing in the original fuse location.
http://ecomodder.com/forum/member-ve...-tap-place.jpg

The relay needs a ground connection on the coil side to activate, and I found one that holds the fuse panel in place.
http://ecomodder.com/forum/member-ve...metal-back.jpg


That's it! The install is pretty simple, and should be easy to remove as well.
The toggle switch on the far right is the enable/disable.
http://ecomodder.com/forum/member-ve...ill-switch.jpg

And here's the momentary switch on the shift knob.
http://ecomodder.com/forum/member-ve...shift-knob.jpg

I'll update this thread after I put some miles on it and verify it works.

I've put about 25 miles on the car since the install. So far I have not had any engine problems except for when I forget that the button actually works and start playing with it :o

I had to get an inspection today and didn't get any trouble from the auto shop or get any feedback of something being horribly wrong. It's only been on for a few miles so that doesn't necessarily much.

It does seems like it takes a second longer for the engine to shut down when using the kill switch vs key off, I'll have to investigate that more. I do like that the ultragauge reports properly every time now with the engine killed. Before, when I would key off, the ultragauge would stop reporting trip and short trip MPG about 50% of the time.

Yeah, I can't wait until mine's done. My UG comes fully back up less than 5% of the time for EOC.

Hi,

Im from the UK. Im loving this forum

Im going to do this mod to my car but iv read that it may be best to do it from the fused that controls the injectors to cut them off.

Am i right in thinking that i will need an Normally Open switch? So when i press it, it makes contact and allow current to flow?

Also i like how you added the toggle switch to enable/disable the function, i think i will also be adding this. May put a cool fighter yet switch for the enable/disable, so it cant be accidentally pressed.

Thanks

Nice idea, OP. I like the write-up too. Thanks.

Depending on how you set it up, you might want to check the setting for the UG itself. For a longtime, my UG cut out for several seconds much of the time when I cut the injectors. Then I learned here about a settings change to how often it attempts a restart or something (search the forum). Fixed it.

I don't know what you are driving, but on my old Civic, I cut into the ground wire for the fuel injector relay. Cuts the injectors off immediately. My toggle is normally closed, switching to off is to open the circuit. I have used it for maybe four or five years without trouble (though I have worn out one switch and broken wires).

Hi, thanks for the reply.

Im driving a Renault Clio 1.2 16v. Cheap little car :)

Well iv just bought a few items off ebay.

5 pin 30A rely
in-line fuse holder
normally open switch
16 gauge wire

So you idea about cutting into the injector relay earth, im guessing i wont been needing the relay i bought.
Would you recommend still using the in-line fuse and the normally open switch?
Im a noob when it comes to car electrics and electronic components.

thanks

Yes, the power off settings on the UG will help this. I had the smart problem on my FIT.


I don't know how much current flows through the injector ground, if it's low enough, a normally closed momentary switch would be okay. I always think of what will happen if my mod fails while I'm driving. If my mod will "brick" my car without serious work to remove the mod, I'm not interested. In my case, I wired the power side of the relay normally closed, so applying current to the control side of the relay will break(open) the circuit and kill the ignitors.

This way, if the my switch fails, I won't be able to use the button to kill the engine. No big deal, I get home safely and fix it. The relay is specifically designed to switch high current loads 1,000's of times so it is less likely to fail. But if it does, I can remove my modified fuse tap, and install the fuse on its original location and be on my way again. I don't even have to get out of the car. I wouldn't want to be trying to splice or solder wires together in my engine bay on the side if the interstate in rush hour. Design for failure.




I have been thinking about changing my kill method. I'm not getting super reliable kills. Probably about 15% of the time, the RPMs hover at 200 or so and the car starts back up even though I'm in neutral with the clutch in. I'll probably start looking in to the injector circuit, or taking in to the key circuit.

Veen, I would recommend not continuing to kill your car with that method. Your vehicle is doing what is called 'dieseling' in essence, your car is spraying fuel and detonating it without spark. Very unhealthy. Go the injector method, it's tried and true.

You should not need and won't want the fuse holder if you go the route I did. I recommend you consider what Veen and Balto said above too. Most importantly, be prepared to experiment and the experience failure. Don't cut into wires without a schematic for the wiring system and consider how a given wire might serve several systems. For example, when I cut my switch, it also cuts the fuel pump. No problem, since I am cutting the engine. But if you have an alarm or a car-immobilizer security system, it could get dicey. Plan carefully. Get a wiring diagram. Always try a reversible version of the mod before a permanent one.

Iv just had a thought.

Would it not be a good idea to just connect into the actual key switch wiring so when the Normally open witch is closed, it replicated turning the key to off mod and when released, it replicated turning it back on.

Iv said before, i know very little about car electrics so yes this method is probably stupid somehow. haha.

The method i do want to follow is the one that involved the fuse for the injectors. believe it was from a thread by bbjsw10.
Cannot add link due to not having enough posts.


Any downsides to this?

I may be looking into the key switch circuit for my car if the injector circuit doesn't work out. My biggest concern with key off is all the other systems it may kill. I doubt electronic key off would lock up the steering column but you can bet I'd test it thoroughly before hitting the road.

Thanks for the head up Balto. With the extra toggle switch, it was easy to disable my kill switch so I didn't use it out of habit. Now I just need to figure out an injector or key off kill... and look into a cleaner product for the engine. I'm sure I added a little carbon build-up with the dieseling

Is there something so much different about a 2009 Fit's wiring compared to a 1996-2000 Civic that means you can't just cut the ground to the fuel injector relay? I did that five years ago on my 1998 Civic. The worst thing that has ever happened has been a switch failure after tens of thousands of uses. All the switch failure required for repair was reconnecting the ground wire with a buttsplice in the car and driving home using key off for engine off coasting. Took less than 5 mins to repair, and failure only happened because of my novice design flaws. Wire failed once. Switch failed once. I moved the wires so they would get less stress from the shifter knob's movements, and later I got a more robust switch. No new issues.

I'm not sure. I haven't really had a chance to study the FIT wiring. I really need to pick up a Haynes manual for the car. I am leaning towards cutting the injector circuit. Do you know how much current generally flows through that circuit?

I am not sure, but if you cut only the ground, that concern is less significant, which is why I chose to do it that way. Try only reversible tests at first. Often the wiring diagrams mislead a little, and we only discover that more components are affected after we have cut a wire. It can be easily repaired, but the wiring aystem in permanently marked, of course.

Im planning on doing this EOC mod within this next week. Just waiting for parts to arrive.

Im planning on dirupting the Crankcase sensor signal to cut the engine as it seems to be the simplest and best way for me to achieve what i want.

I have a question regarding wiring though. Im wanting to add a toggle switch inline with the momentary closed switch, so that when the toggle switch is in the off position the momentary switch will not be able to interupt the sensor singal. Im not 100% sure how to go about doing this because if its in line with the momantary switch and the toggle switch is off, then the signal will also be interupted this way, and thats not what i want. I want to be able to just make the momentary switch active or deactive.

thanks

Because you are interrupting the signal directly with the momentary switch, it will be difficult to also add a toggle switch. The only method I can think of is to add a relay.

Use a relay to interrupt your crankcase signal. The toggle switch and momentary switch in series would be used to apply power to the control (coil) side of the relay. You could do the same thing with a FET or transistor but a relay is probably simpler.

It might be simplest, but consider that the car's OEM switch probably cuts fueling at the injectors and the pump as the primary difference between "run" and "on." If you cut just the crank case signal, the car will probably run-on a little until it cuts fuel. Doesn't that mean fuel getting pumped into an engine not running very well anymore? Won't that mean possibly fouled plugs, and maybe a pligged CAT? Better to stop the injectors on a dime, by cutting their power, no?

I actually bought a 5 pin relay and a momentary off/on switch as i was originally going to do this mod via the injector fuse. I dont suppose you would be able to give me some advice on how i would have to wire the relay and everything in to do what you have suggested? I dont really have any idea where id start with relays.


Thanks for that suggestion. as mentioned above, i was originally going to kill the injectors by using a relay to disrupt the signal going to the injector fuse. But i have no idea where the injector fuse is on my car and from reading posts By 'bdc' in this thread http://ecomodder.com/forum/showthrea...-how-4356.html it convinced me to just go the route of the crankcase signal. According to bdc the ecu should cut the ignotion and injectors as soon as it senses a loss of signal from the crankcase to stop it causing damage.


Any other suggestions or advice is much appreciated though.

thanks

hey guys, so regarding my cam sensor.

it only has 2 wires. ive been told that one will be an earth wire and the other will be a signal/power wire.

Am i still able to plug EOC switch into this? Does it matter which wire i disrupt. Ground or live?

Cheers

It won't matter much. But I would choose the ground wire. You can test by disconnecting each wire and see if there is any difference in how the car shuts down.

Hey, i woul struggle to find do this test as i have no idea where those 2 wires go to. they go into a bundle of other wires and all over the engine compartment.

Do you have any idea which wire would be the ground wire if the colour of the 2 wires were green and white.
My guess would say the green one would probs be the ground wire.

Since im probably unable to test which wire shut off the engine best, would i be best to kill the power or the ground.

thanks

You need a good wiring diagram for your car. When you have that, with patience you can test disconnecting wires without cutting them by disconnecting individual wires in the OEM connectors. You'll want to test because even the wiring schematic will not give you all the info you want and so disconnecting something that seems to affect one system might turn out to affect two or three systems.

The OEMs did not make the cars or their wiring diagrams with modders and hackers in mind! Hahahaha!

Sorry I can't offer more than that.

Have you searched this forum for others who have completed injector kills?

Hi, thanks for the advice.
Yeah ive alread had a really good read of alot of threads on there and that why i decided to go down the route of the crankshaft sensor.

Renault dont seem to like to give people much info about there cars at all. Even the haynes manuals are pretty usless and asking on the renault forum they just think we are nuts haha.