5.3 Wiring Tech

95limitedzj · Jul 8, 2013

I have acquired a jeep cj7 with the start of a 5.3 th350 np205 swap done. The engine harness was supposedly reworked and ecu tuned by wait4me. I have 5 main wires coming off the engine harness (3 switched 12v, 1 12v constant, and 1 starter solenoid) along with 10 or so smaller wires for oil pressure, fuel pump relay, diagnostic port, etc. all labeled. I also have the current performance fuse/relay kit (SA-1000 Fuse/Relay Center from Current Performance Wiring). The body harness in the jeep seems to be an EZ Wiring kit from the old motor swap that was in the jeep (LT1). My question is what is the best way to mate these 3 harnesses or would it be easier to ditch 1 of them. The EZ wiring harness that is in the jeep now is already connected to the lights,blinkers, ignition switch and so on and I would prefer to leave all of that alone if possible. I would just need to tap the 12v switched in it and run my 12v switched wires from the engine harness to relays that are switched by that tap?

P.S. I hate wiring and there's a case of beer in it for anyone who can set me straight.

zjtrey · Jul 8, 2013

it sounds like you have all you need in the 5.3 harness and it shouldn't be difficult to use whats there for ignition and lights.. the lights and blinkers will be seperate from your engine harness anyway

I'm guessing the previous owner didn't give you the info wait4me provided with the harness? if not you can probably call them and get the info on hooking up the stubbed out wires..

letting folks know where you're located would help in finding someone willing to help you get it going.

95limitedzj · Jul 8, 2013

Yeah I know I can get the motor started with just the 5 wire hookup from wait4me. But I'd like to have everything else (lights,gauges, accesories) controlled with the existing harness. Im trying to figure out where and what i need to tap for the relays off the existing harness to make the two harnesses work together. O and I'm in Auburn, but was really more talking about advice through the board, if someone wanted to kick tires and work through it here, beer's on the house..

zjtrey · Jul 8, 2013

do you know what year your 5.3 and harness are from? you can find pinouts and such at lt1swap.com by the year model.. if you don't know the year you can get most everything by the color of the harness connectors at the pcm.. they'll either be red and blue or blue and green (there may be other variations too.. I'm shooting from the hip on that one..)

lt1swap.com gives you a basic run down of how the harness works..

do some reading there and start posting your questions.. also contact wait4me and see if they have some info on their harness work and it shouldn't be difficult to get everything working the way you want it..

95limitedzj · Jul 8, 2013

I'm not concerned with the wait4me part. It's 3 12v switched wire a 12v constant and a starter solenoid wire that need to be hooked up and a fuel pump relay wire. The remaining wires off the harness are either gauge/obd2 diag/fans/ac stuff that isn't crucial to start with. I would like to do it in the least rigged way possible which is why I'm asking here if I can just tap the start/run wire from the column of the original harness for the 12v switched and constant 12v. Or do I need to run separate relays and power to each one of those legs coming off the wait4me engine harness.

TBItoy · Jul 8, 2013

Yes you can use your current chassis/body harness.

It was providing power to the harness/ecm of the LT1. No reason it couldn't do the same for the 5.3

Unless I'm missing what you're asking.... :dunno:

zjtrey · Jul 8, 2013

what i would do is have the switched 12v (existing ignition) power relays for the pcm and sensors.. then you won't have to modify your existing body harness.

Some folks run the whole engine harness off of 2 or 3 relays.

You probably want to run individual relays for the switched power legs coming off the wait4me harness. I would definitely run a dedicated relay for the fuel pump, the pcm should supply ground to the fuel pump relay so it shouldn't really have anything to do with the ignition switch, when the pcm comes on, it will turn the fuel pump on to prime it, then run constantly after startup.

do you plan to run an electric fan? if so are you going to turn it on manually or let the pcm do that? the low side on mine comes on with the pcm and i have an override switch for hi.. if you run a clutch fan that moot..

I have a dedicated relay for the sensors, and one for the injectors.. i may have too many relays but its very dependable..

am i helping or confusing?

95limitedzj · Jul 8, 2013

It all makes sense, but when I get to the garage and look at it I get overwhelmed and dont know where to start. Just need to do 1 at a time I guess. It has a taurus efan in it, not sure what the temp setting is at from wait4me so I may just run it on a switch, theres a relay set up for it already in the current performance harness. Appreciate the help guys, the 5.3 thread on pirate has died I guess.. free beers for anyone who wants to come have one.