PSI Conversion

[MechMan]

I am looking inot the PSI conversion wiring harness for my LS3 swap. Has anyone used them? It looks like it is pretty simple. I was also trying to see how to wire up their fan relay kit. Any help would be most appreciated

 

[fleming442]

I'll be installing one in a few weeks. The GM PCMs have 2 negative triggers for the fans- 1 low, 1 high.

 

[MechMan]

I see the PSI harness has two fan wires in the under dash wire bundle. I would just run those wires to the relay per their instructions i guess?

 

[fleming442]

It depends on your fan setup.

 

[MechMan]

Also for the people that has use the PSI harness where did you mount the PCM? CAn it fit in the same location as the stock computer?

 

[Texas82GP]

Also for the people that has use the PSI harness where did you mount the PCM? CAn it fit in the same location as the stock computer?

We used a PSI harness on my brother's LS swapped 78 Z28. It was setup for the PCM to be inside the car. We put his above the glove box. You could definately get the harness through the firewall in the stock location on a G-Body (low on the passenger side of the firewall, behind the inner fender), but I'm not sure if the harness is long enough to reach over to the stock kick panel location for the PCM. The main trunk of the PSI harness originates over the back of the passenger valve cover of the LS and then branches out from there. On my brother's car, we went right through the firewall, right there over the valve cover. I don't remember having a lot of extra length in the harness under the dash so I don't think it will reach the kick panel. Call them (PSI) and see if they will give you a measurement and if/how much it would cost for them to build you a longer harness.

 

[Texas82GP]

Also, we used a Gen III PCM (05 Silverado) as we wanted a drive by cable throttle body. I think that PCM is fatter than the stock G Body PCM so I'm not sure if it would fit behind the kick panel.

 

[Texas82GP]

You should be able to see here where we went through the firewall on my brother's car.

 

[MechMan]

Also, we used a Gen III PCM (05 Silverado) as we wanted a drive by cable throttle body. I think that PCM is fatter than the stock G Body PCM so I'm not sure if it would fit behind the kick panel.

Thats what I will be running since i also want to keep the car DBC.

 

[MechMan]

You should be able to see here where we went through the firewall on my brother's car.

View attachment 105566

Thank you. I was kinda hoping it would fit in the stock location because I am trying to figure out how and where to run the wires for the fuel pump and cooling fans. So far everwhere i look people are saying fitting the PCM under the dash is very tight.