1996 chevy p30 5.7L Obd port wasn't working. After I looked under the dash it's apparent someone has cut all the wires and never wires them back in. I guess there was front end damage so I assume they just never wired it back up. I have a pin layout for the port but where do the wires come From? The computer or is there another data source? I wanted to use an Aftermarket obd2 HUD for a tachometer. But it says incompatible. Please help
The wires you are looking for would normally be in the loom close by if they cut them off as you say.
So that means looking at the colors of the wires on the port and finding them in the loom.
One possibility that comes to mind is that they replaced the damaged loom because it was burnt and the replacement was from an older car which may mean that the wires just don't exist at that point. Then you will be in need of seaching out the source4 feeds for all the functions. Things like ignition supply will be easy, others not so.