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

  • You are really going to need a high quality wiring diagram for your vehicle. And that really means the diagram as provided by the manufacturer. And to do this right you may well have to remove the instrument panel from the vehicle. And thats a huge job, not for the casual home mechanic. But don’t just ask here. Take your vehicle to a mechanic, describe the issue and get a $$ estimate.
    – zipzit
    May 13 at 3:34
  • @zipzit and it's a job I would not suggest many mechanics would be good at either, while they may be excellent at their own trade, being a vehicle electrician is not thier forté. And I have worked with many car and commercial vehicle mechanics who happily paid for my skills...
    – Solar Mike
    May 13 at 5:02
  • Does your obd device support J1850 protocol?
    – narkeleptk
    May 13 at 12:16

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.

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