Fuel Injector Kill Switch: 1990 Honda CRX HF (How To W/ Pics)

[jasonst]

I'm not the "How To Guy" or anything, but hopefully this will be of help.

Purpose: A switch to immediately kill the injectors while keeping lights, signals and instrumentation.

Decide where you want to place your switch.

I wanted mine to be super accessible, but not super noticeable. I wanted it close to my right hand and close to the shifter, but I didn't want to cut a hole in something important. I preferred it be on something I could easily replace if I botched it.

I chose the small access cover under the emergency brake lever:


Once you've chosen the perfect spot it's time to move on to the PCM-FI Relay.

Remove panel under steering wheel to open up the area a bit:


Here's a good link showing how to gain access to and remove the PCM-FI Relay:
PGM-FI Main Relay problems and fixes

This is what you're looking for:


After talking with several people I decided to wire my switch into the ground wire of the PCM-FI Relay. I absolutely hated cutting into the wiring harness, but I couldn't think of a way to avoid this.








Put the PCM-FI Relay back where you got it, (no swearing allowed) along with the hood release and button up the dash.

Here's where the wires come out under the emergency brake lever:


I wanted the switch on my side of the emergency brake lever:




I'll update this thread with my thoughts after I've driven for a few days.

[FXSTi]

Jason,

Nice how to. Is that a momentary interrupt switch or an on off?

I keep wondering how long it will be before I cut into my 2011 Fiesta. Someone smarter than me will have to figure out what wire to cut and where.

Kirk

[jasonst]

On/Off

[California98Civic]

Nicely done. Looks good. Stealthy.

[IsaacMTSU]

How do you like the switch? I have the usual bad relay problems, sometimes it just wont click and I can't restart. I guess this kills the whole relay and I would need a good one for this to work?

[myrefugeisintheLord]

Good write up Jasonst.

I wanted to add a kill switch in my 91 CRX HF. But I didn't want to kill the ECU. Only the injectors. So I had to do some digging and with a lot of help from a friend (WeatherSpotter), I finished the install last night. Here's my "How To".

The supplies I used are:
1, 5 pin Bosch like relay
1 momentary switch (normally open)
1 fork, or preferably ring connector
6 female insulated spade connectors
2 male insulated spade connectors
14 & 18 gauge wires
electrical tape
solder
loom

Tools needed:
10mm socket
philips screwdriver
an electrical crimping/stripping/cutting tool
solder gun



- -<>- -<>- -<>- -<>- -<>- -<>- -<>- -<>- -<>- -<>- -<>- -

First off, here's the page in my 91 CRX electrical manual for the injectors.


And here is a wiring diagram I made to show what I did. (let me know if I can improve it.)


Here, I have taken the injector resistor box out from its spot and exposed the wiring harness more.


You cut which ever side of the injector power wire you want. I did the red side, as I thought everything would tuck in better after things were put away. And I can disconnect the resistor box and replace it with a stock one later. No harm done to the main wiring harness.

(Also, use one female connector on one side of the injector power wire, and one male connector on the other, in case you want to bypass your switch. )

Next, add a power lead to your relay (Pin 86). I used an already fused ignition wire. The ignition wire that is hot in the Run or Start position already had a quick connect splice in it, so I used that spot. I also soldered the power wire in. (I will be revisiting that connection to wrap it up better.)

If you would like to connect directly to the battery, you will need to add an in-line fuse to that wire, with a 15A fuse in it.

Next, add your momentary, or rocker switch. Ideas for what to use and/or where to put it can be found here: Kill Switch (EOC): Where did you install your activator? And what did you use?

I chose to use a momentary switch, and I attached it to my shifter nob. Because the switch doesn't carry much current, I used 18 gauge wire for this (14 gauge for everything else). One pin on the switch gets grounded, and the other goes to the relay (Pin 85). I soldered the wires to the switch, and used small bits of heat shrink tubing on each post.

Remove your shifter nob, and the lower dash piece. It's held in by 6 screws.

Keep the wires semi long as your shifter is a moving component!

Close up of the ground location. Better to use a ring end, appose to a fork, but I don't have any rings of the right size, right now.

It's a good opportunity to clean this area up!!

I left a small section of the wires uncovered. when I got the shifter arm back through the leather boot, it's too tight of a fit! Especially with the shifter nob on too.




Next you can attach your switch any way you like. I chose to use just electrical tape, as it allowed me to get the precise location that I wanted, and a temporary situation that I could adjust in time.





Close enough to reach easily, but not so close that I'll be bumping it.

Now it's time to wire up the relay. I chose to put it near where the hood latch release usually is. (I've relocated mine.)

The picture pretty much says it all.

Pin 87 stays open.

Loom up your wires. (I didn't loom everything.)



Put your injector resistor box back in place.

I left a length of loose wires on that end, in case I wanted to pull the box out again. I'll probably shorten the wires later.

And attach your relay to wherever suits you.


And test it out!

Mine works great! Only drawback is that it lights up the CEL. You can turn the key off, and back on, and the CEL will be gone. But as long as the key stays in the Run position, and you use the kill switch just once, you'll have a CEL, at least with an 88-91 CRX.

I hope this write-up helps some of you! And another HUGE thanks to WeatherSpotter for helping me with the wiring!!!

[California98Civic]

Nice work. On mine the CEL goes back off whenever I re-engage the injectors. I have actually come to think of it as visual confirmation that the injectors are off, and that they are back on.

[razor02097]

Originally Posted by California98Civic

Nice work. On mine the CEL goes back off whenever I re-engage the injectors. I have actually come to think of it as visual confirmation that the injectors are off, and that they are back on.

Would this mod benefit a vehicle that uses DFCO? Do you just use it down hills and such?

[Gealii]

Originally Posted by razor02097

Would this mod benefit a vehicle that uses DFCO? Do you just use it down hills and such?

It would benefit a vehicle with DFCO because DFCO is not always in affect where the switch would be able to have DFCO at any point and then instead of being in gear causing more drag it can be put into neutral coasting further. For example my car being an '02 i cant get DFCO under 45mph.
Search "Pulse and Glide", I would use it whenever coasting for a good distance.