where are you guys mounting your PCM? PSI Conversion harness with PCM

I bought a 5.3 LM7 swapped 86 Monte Carlo SS, and the prior owner left all the wiring in the driver front fender area. The car is an incomplete project, still needs fans wired up, tachometer, speedometer, some other gauges, and not sure what else. The car runs and drives (though somewhat rough, and rich so it needs a tune at the very least).

The wiring and PCM were supplied by PSI Conversion. According to PSI Conversion a lot of the wiring should have been inside the cabin, underneath the passenger side dash / glovebox area circled in red on the image below.

I feel kind of inclined to leave the PCM wiring section of the harness in the engine bay becasue running it back into the intended area under the dash will either require me unplugging the rest of the engine harness to route it through the firewall from the interior, or having me cut a large enough hole in the firewall to route the PCM harness through.

Where do you guys mount your PCM? OBDII port? I would try to run the engine light back to the dash.




Currently how the engine wiring sits:

Rt Jam said:

If PSI Conversion said it's supposed to be inside the car. They would have made the wires long enough to reach inside. This is a big factor in determining where things get mounted when using a terminated harness.

Mine is a Holley Terminator Xmax. I ran all the wires through the factory 2" hole just behind the right front wheel and mounted my ECU under the glove box.



View attachment 248383View attachment 248384

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That looks clean, I may end up going this route too and putting it in the car. I need to find the 2" hole in the firewall to see if I can pass the PCM connectors through, otherwise I will have to keep it in the engine bay if its too small.