Wiring: Fuel Gauge

     I have began to re-do some of the wiring on the Datsun as it is a pile of poop. Half of the instruments on the dashboard work. The only thing that works is the speedometer gauge, although it reads 10 miles over than the actual speed.

     For reference, something that's helped a lot is this online wiring diagram that I found here. Although that wiring diagram is for a 1970+ Datsun 510 w/ manual transmission, it should be very similar to mine. Picture of wiring diagram below.

     So far what I've done w/ the wiring is getting my fuel gauge to work! It was really important to get that to work since I want to know how much gasoline I had left. It was really easy to identify the problem after looking at the wiring diagram. On the diagram, there's a yellow cable that goes from the gas tank unit down towards a wiring harness where other cables are connected, then to the instrument cluster. The previous owner had wired the fuel gauge wire to the heater, and after a while it had melted and blew a fuse! There was no insulation between the fuel gauge wire, and other wires(see below).

I had then cut the yellow wire to a specific length and crimped new wire in between both ends.

After crimping the wires together, I had then reconnected the fuel gauge wire from the heater, to the other identical harness. Although they looked similar, they weren't. After turning the key to the ignition, nothing happened. I thought that the fuel gauge was broken. I actually found out that the car must be on for the fuel gauge to display. Now I have a working fuel gauge!