[wilf leek]

15A sounds low for a headlamp circuit. Two 60Watt lamps alone draw 10 amps, without the sidelights etc. I would have thought 20A minimum for the fuse.

Headlamps (and other high-current-draw things like radiator fan)should run through a relay so that the switch is only switching the (low) relay coil current. Even so, the feed to the relay (i.e. high power side) should still run through a fuse.

Fuel gauge feed is usually via a voltage stabiliser to elimintae guage fluctuations from varying system voltages.

HTH