[urq] Another electrical question...

[Thatcher Hubbard]

...though it's probably close to being the last, at least for now. 
I've got all of my wire harnesses run where they ought to be now,
everything that belongs in the engine bay is through the bulkhead, the
RPM and Fuel Pump ground trigger wires are  split off the harness
behind the dash and run over to the driver's side.  All I really need
now are two wires from my 12v terminal under the dash for the fuel
injectors and the ignition coil.

Can anyone tell me exactly which pin on the fusebox of an '83 (under
dash fusebox) is the one that the fuel pump trigger comes in on? 
Using a multi-meter, I found two pins that gave me a closed circuit
when I put the postive probe of the MM into the ground trigger socket
where the FP relay plugs in.

Also, where did the RPM signal come from originally?  The ECU, the coil, ???

Thanks to anyone who can provide some enlightenment here, I feel like
I'm actually a couple weeks away on this thing.