Hey HT here is my first write up. I believe this would be model specific because other cars/model years have the relay located somewhere else under the dash. My Stock 99 Coupe Ex was stolen at the end of July and recovered a week later. I wanted to install some new safety measures after seeing how easy it was for thieves to break in and drive away with my car. This thread is to document the steps I took to install a PGM-FI/fuel pump relay kill switch. I will be installing a few more different kill switches just to have an extra level of security in the future. Here is an image of everything I used had to buy except the toggle/rocker switch.
-Wire strip/Crimping tool
-Butt Splice connectors
-Male/Female connectors
-16 gauge wire
-wire wrap
-Heat shrink wrap
-Toggle switch with wires already connected.






What we need to do first is locate and access the PHM-FI. Begin by taking off this lower panel covering the ECU on the passenger side. It pops off and has one difficult piece holding it in near the bottom that you can sticking out slightly. I just wiggled it back and forth until it popped off.



Next what I did was lower the glove compartment by pinching the edges. Now you remove this edge piece being held in with one phillips head screw and then popped it off.



After removing this I went over to the door side near the tweeter and removed this Phillips head screw and popped off the covering. This allows me to see the wiring and what I was doing and where I was going to run my wires.



Then after removing this I dropped the glove compartment by using a 9 or 8mm bolt because I was afraid to strip the screw. They are connected underneath on the cross bar. I would recommend taking the whole hinge off instead of disconnecting from the hinge because it makes the install easier and has a smaller chance of bending anything.





Afterwards this is what you should be looking at.




At this point you should look at the black box on the right hand side which has a brown thing plugged into it. This is the main fuel relay, also called the PGM-FI relay in the Haynes manual.



There is a pinch plug so I would just gently pinch it and then I would pull on it to remove it. This is what it looks like and what you'll be cutting into.



From here I tested with a multimeter to find out which wire I was going to cut into. With the keys in the off position, I tested each of the wires to find which wire was hot at all times. It was the bottom left, I will not tap into that. Now I turned the keys to the run position (two clicks) and tested each of them to find out which had 12v going through them. It was two away from the hot wire and on the bottom. So it was one left from the bottom right. Then I traced the wire to the back and singled it out.



Remove the negative battery terminal before you cut into the wires!!!

Then I cut into it about an inch or two away from the connector so I had room to strip and add connectors.

Then I added heat shrink and added butt splice connectors to each side and crimped them. (I highly recommend to buy a separate crimp tool, I had a tough time getting my big *** 4 in 1 tool in this tight spot). Heat shrink after you have it crimped.


Then I measured how far it would be to where I wanted my kill switch and cut some 16 gauge wire to length. Then I made a second piece the same length for the other connection. I took my switch and decided to use male and female quick disconnects in case something happens and I want to move my kill switch. I did the same thing of heat shrink-crimp-heat. Here is what the switch and the connection looks like. I messed up and forgot to add heat shrink on the switch side so I will redo this when I replace my cabin air filter. I also crimped and heat shrinked the 16 gauge wire to the butt connector to complete the whole circuit.



Then I connected everything together all the way from the switch to the relay. and put the battery terminal back on. I also added wire covering to prevent any chafing or grounding out.


Here's what it looks like when I connected it back to the relay and plugged it in. Don't talk bad about my taping job haha I was all jumped up on coffee and sweating my *** off this morning.


Then I took out my center console and ran the wiring up to where I wanted my kill switch. Here's how it looks under everything. First pic is behind the glove compartment and second pic is behind the cup holders, third pic is it going up to the center console area.





Next I attached my kill switch to a sneaky spot. I will move it afterwards this is just a test spot for the first week or so.



Now I connected everything back together! It looks pretty clean and no one would know where my switch is. Ive tested it out and it works really good. If you turn your car to the run position and you hear nothing, but your car cranks that is good. When you flip the switch you should be able to hear the fuel pump and start your car. I hope this helps y'all out.

 

you should have used the BLACK (ground) wire especially when you are using crimp connectors instead of soldering+heatshrink tubing. Yes, it does the same thing and there is no voltage running through the switch.

 

Damn I didn't really think about having voltage going through the whole thing. I will switch it out next time I go under the dash. Thank you for the information I will use it.

 

Not a problem. Using the ground minimizes the chances of blowing fuses

 

This is a good idea. But I think it might be easier and better if you just used the clutch inhibitor switch at the pedal. Use a switch to keep an open circuit. Then the key won't even turn the motor over and you won't trigger a possible ECM check engine light when it thinks the PGM-Fi relay went bad.