Ok. Im going to post this because I know this question has been asked before, but never gets answered. Heres how my Zex kit is hooked up to a Harlan window switch(which provided a switched ground).

First, get a 4 prong 30amp automotive relay. Now, first thing i did was wire up the 12v(from my arming switch), ground, a tach signal for the window switch. That gets that crap out of the way.

Now, take the nitrous switched12v wire (going to the NMU from the arming switch) and cut it. The switched 12v part of that cut line goes onto the prong called "switch" on your relay. The other end of that cut nitrous wire(this is the part that going to the NUM, NOT from the switch) needs wired up to the "load" prong of the relay.

Now, this leaves 2 prongs left on the relay(one is called "battery" other is called "ground"). For the battery prong, I ran a switched 12v from my gauges fused wire(from my fuse panel). So, its on anytime the car is on. This prong of the relay will have power anytime the car is running...but it wont go anywhere unless the window switch is within its "window". Remember, the window switch isnt even on unless my arming switch is on cause thats where is 12v wire is coming from.

Now, that last prong is the "ground" prong on the relay. This is the prong that the Harlan window switch white wire(switched ground) attaches too.

Then, what happens is that unless the window switch is within its window of operation...there is NO ground provided to the relay So, the kit does not activate reguardless of the TPS(which isnt on). Also, I put a 1amp inline fuse between the white wire and the relay to protect the window switchs 1.5amp max capacity from ever being challanged. Hope This helps someone. I had to figure it out for myself cause Zex tech would not answer my emails about this....however, they answered all my questions about buying their product, figures!

 

that will work, but i would not reccomend doing it that way.

What i would do is:

+12 -----ZEX ARM SWITCH-----------Relay (jumper pins 85 and 30)(pins 85 (one part of coil) and 30 "switched input") ------ then the switched output (pin 87) to the NMU

For the 86 pin, connect this to the Harlan unit.

this way, you only energize the relay when the System is armed,

Ryan.

 

Yeah....that definently sounds better. Originally, thats what i wanted to do...however, someone else suggested otherwise and changed my mind for me. Im going to put it how i wanted it, cause i didnt like the idea of it having power all the time either. Thanks, later.

 

i have a zex kit and i love it. i ve never heard about a harlan window switch though! i took a different approach than u did i guess. I bought the msd timing control module that piggybacks to the msd 6AL box i also have. a have many modifications on my 95 trans am but i was wondering if my adjustments for nitrous were correct. I m spraying a 125 shot to my engine i also have a holley fuel pressure regulator which is set at 51 p.s.i. i retard my timing about 5 degrees and use about 105 octane aviation fuel evry time i spray. DO you think these settings are good or do they need changing. i just want to make sure i dont harm my engine while spraying. SO what do u think about these settings are they good or bad and what are yours like. i havent found many people with a ZEX kit on a LT1 so i would like your opinion. THANKS ALOT PLEASE POST A REPLY BACK THANKS!!!!!!!!!!!!!

 

I am rebuilding my engine now because of detonation problems i had. However, it was not because of the nitrous. It would only ping off the spray. On the spray...it was actually better. I think it was because of all the extra fuel its getting then. As for my setup. I have autotap to log stuff and on 125(when my car ran right) I got 0 knock retard. Which means...I didnt need to pull any timing. Also, never pulled any for the 75, 100(of course). This is always on sunoco ulta 94 gas. No race gas or octane booster. I dont have adjustable fuel pressure regulator. AFPR...apparently, they are useless on 94+ cars cause the computer compenstes over time anyhow. My zex kit has always done a great job of increasing fuel pressure(yours did come with an inline pump didnt it?). I have a fuel pressure gauge in my car and it spikes really high on spray every time. I forget what it actually hits(havent drivin my car in over a month). Was on stock injectors also. Anyhow, i love the kit also and would not trade it for anything else. It might not deliver 300hp shots like some...but then again, i dont ever want to run a 300shot...so thats fine with me. Its a very safe and reliable kit. Also, I made custom puge kit for it so it spray in front of my windshild(pics on website). Later

Oh yeah...If you dont already have a remote bottle opener, get one. Nitrous sucks on the street without it.