Why are there multiple Pgm-fi fuses in a fuse boxes?

Question

I’m just looking at the fuse diagram for 1996 to 2000 Civic which is the second part in the link: https://honda-tech.com/how-tos/a/honda-civic-fuse-box-diagrams-374430

I notice the pgm-fi exists in multiple places in the hood fuse box: 13 and 31 aswell as the dash fuse box 44.

Why so?

I also notice the pgm-fi main relay unit exist under the dash in the car but isn’t shown in the diagrams while other less important relays are. Did they forget to include it in the diagrams which actually appear in the vehicle or is there a reason they didn’t include it as part of the diagrams?

Answer 1

A relay is usually supplied by two supplies, one a controlling supply, the other from the battery, either direct or through an ignition controlled circuit.

Both need to be fused, which explains why you see three fuses in total.

As for the relay, it may be shown on a separate diagram as sometimes the circuits are separated for clarity and also for showing things that were factory options.

Having one large single wiring diagram with absolutely everything shown would confuse most people... However I would prefer it as it would mean less page turning, but then I can read those diagrams.