(88 L67 swap questions). Added alt question

[Zeik75]

Why does the 5v reference signal go into the firewall passthrough on my 98 harness? What is it signaling inside the car? My computer pinout only say to connect it to the tps, map, egr on one pin and then the ac pressure sensor on another pin. Do I even need the 5v intot the cabin?

[michtom]

You do need 5 volt reference for fuel tank pressure sensor.

[MattStrike]

I concur. It's only that sensor, nothing else uses it.

[Zeik75]

Sweet! Who needs that sensor anyway!

[Zeik75]

Another question, this time about the alternator wiring. Where should the wires from the alt end up going? Stock on the 88 had pin L of the alt wired into a splice that went to the ERG power, A/C cutout relay, then those three join and go through the C265 connector and went into fuse 5 of the relay center, which also powers the evap purge and brake switch. However the 98 computer wants pin L of the alt sent to it. Do I even need to splice the alt back into the old 88 wiring?

[MattStrike]

No. Old way: ign switch powers the Field current supply , new way pcm powers it. Don't tie them together, keep them separate.

[Zeik75]

I have to change some of the info. Pin F/I of the alt was wired into the splice, I have pin L going to the comp and the computers charge light sognal into the dash. Does that make more sense lol?