PSI Harness Hookup (How I did mine)

[skyphix]

Hey everyone,
I pieced together a few different things I found to hook up my PSI Harness but it took a bit of trial and error. I thought I'd post how I did mine here and provide a place for anyone to ask questions that I might be able to answer. I'll update the thread with photos tonight.

Bulkhead image borrowed from several places floating around the internet, modified for my uses.

1) I moved my battery to the drivers side and used the donor battery cables. I routed the positive battery cable the same as the donor - mounted the junction block to the side of the accessory drive, routing the positive battery cable under the accessory drive tight against the block, under the exhaust manifold, to the starter. The ground I connected directly to the side of the block where the accessory drive bolts on the side (not the face of the block.) My donors negative battery cable had an extra wire coming out of it, so I grounded that to the drivers side fender.

2) I ran the two power wires from the PSI engine-side harness (red wires, big ring terminals) to the same stud on the starter that the positive battery cable connects to. This provides a little tricky because they end up tight to the exhaust manifold - though not touching, it made me a bit nervous, so I tucked them inside the heat shield that snaps over the starter and wrapped the remainder in heat reflective tape good to 2000 degree non-contact and 500 degree contact.

3) I ran the pink wire (second down from the top on the left side of the bulkhead connector) to the "Ignition Signal" wire on the PSI Fuse block. I also used this to trigger the fuel pump relay.

4) I grounded the passenger side of the block (I used the AC mounting holes - any unused threaded hole in the block that is away from the exhaust will work) to the passenger side of the frame using a Grounding strap. I picked up my grounding strap in the Help section of the local parts store.

5) There is a ground with a ring terminal in the engine side of the PSI harness - I grounded this to the rear of the drivers side head.

6) I ran my harness through a 2" hole I drilled just to the rear of the intake on the drivers side. I had a couple of square holes here, and I just drilled the 2" hole around one of them. This put the harness entering the cab behind the heater controls. This worked great for me, but I have a non-AC Dash... so you may need to adjust yours if you have AC.

7) Fuel tank wiring: This was actually pretty easy - I used the same pink wire I used for ignition signaling to signal the fuel pump relay. A simple T-Splice and adding the PSI supplied terminal, then plugging into the relay per their instructions. I then added a 15A inline fuse to the "power feed" wire that I connected to the terminal on the relay, again, per PSI instructions. I used a 12G wire for this - probably overkill but I don't like fires. I picked up some 2 pin weatherpak connectors (I bought mine with pigtails from Del-City - expensive but cheaper than the Weatherpak tool) to connect to the 1987 Fuel pump sender. Grey is power, Purple is level signal. You should already have a wire going to your original sender if you don't have a factory EFI tank. I used that single wire and hooked it to the purple side of the weatherpak connector, and my new fused power wire to the grey side.

8) For the ground on the in-cab portion of the PSI harness (black ring terminal) I just used a self tapping screw through the firewall. Probably not ideal but it works.

9) I currently have my wiring harness and PCM mounted up behind my dash... pretty much with just zip ties. Its not perfect, but its secure and keeps everything out of the way and hidden. I wanted to maintain my glove box so I didnt want to put it there. Again, having a low option, no AC dash really helps with behind dash space.



That's everything I can think of right now... I'll post more photos tonight.

[Chvy2NV]

[skyphix]

Originally Posted by Chvy2NV

Hah, what would you like to see? I'm still tidying up the wiring so its all easily accessible as of right now.

[Chvy2NV]

Haha. Pics are always good. Where did you run the cables

[skyphix]

I drilled a 2" hole just inside the firewall recess and ran everything in behind the dash. I've got everything pulled back down and laying on the floor right now while I finalize everything. Ultimately I'm going to tuck the wiring back up under the dash and hide the PCM there as well. Probably just with zip ties or velcro again, to be honest.



You can see, the arrow on the right is the PSI harness and the arrow on the left is where my fuel pump power, fuel level sender signal, and power on crank signal go back into the cab. I am 100% certain there is a better way to achieve all of these with under dash wiring, but the under dash wiring in my truck is so bad, there was no good way to make it happen short of rewiring the truck completely. This is working great - though I need to add a grommet to the hole on the left, the split loom is protecting the wiring at least for now.

You can see in the photo below that I used the junction block and factory battery cables from my 2006 Yukon donor. They worked perfectly besides having to relocate the battery, which isn't really that big of a deal and I wanted to anyway since I am using the factory air tract as well. The split loom coming out of the junction block is the constant power feed for both the PCM and the factory chassis harness. I've used this junction block to add more constant power circuits in the cab as well (fused and/or relayed as appropriate.) The blue arrow points to an unused cable that was part of the positive battery cable has since been trimmed and sealed until its needed again.



I'll go take some better photos after work this afternoon, but hopefully thats a start.

[Chvy2NV]

cool man !