Title pretty much sums it up. Friend of mine has a v10 in a 3/4 ton pickup. He replaced the alternator and it started overcharging. Shut it off and now he has lost all gauges, fuel pump, dome light and cigarette lighter. All the fuses are testing good and the OBD2 will not link to the matco scan tool we have access too. Any ideas??????? Computer maybe???? It was just replaced by the dealer for almost a thousand bucks so he is hoping that is not the problem. Can a person get another one from a salvage yard and try that?

Fried PCM

Would that be the ECM under the hood on the passenger side firewall? Can one from a salvage yard be bought and tried without dealer flashing it?

Dome light and cigarette lighter have nothing to do with the ECM working. I'd start checking for a bad fusible link or some other reason for no power. Find a wiring diagram and trace the hot wires. You said all the fuses checked good does that include the under hood stuff and well as the interior ones? Do the dash warning lights come on when you turn on the key?

Is the battery itself OK? Overcharge could have cooked it. A test light and voltmeter should tell.

By checking the fuses , what did you do ? did you just check the fuse or did you check and see if there was voltage across each one . I think its a fuseable link somewhere .

I tested all fuses with a test lite. I tested for power at obd2 port. Contacted local dealership and they said pcm issues also. Have a new one ordered.

Tested all fuses under hood, inside cab next to drivers door and there is power at the obd2 port under the dash. All were tested with a stab light. Headlights work fine. Door dinger works with key in the off position but stops making noise when key is turned to acc or run position. Fuse for the cigarette lighter is good but lighter, horn and interior lights will not turn on. The tail and brake lights work also. Engine will crank over with key but no fuel pump or spark. Battery has been replaced already since overcharging. Have not been able to locate a fusible link. That was the first struggle to look for. IOD fuse was removed and replaced after testing with a test light just to verify good connection in fuse panel.

Replaced the ECM with a refurbished one. The pickup now starts and runs. Lighter socket works now. Still no gauges, no dome light or airbags. Looks like the CTM computer fried as well as the ECM. This has been an electrical nightmare!