Does anyone have a .picture of the harness that connects directly to either the rear or midship tank sending unit?
Trying to see if its a two pin harness at the sender that ultimately turns into a single green wire.

I'm planning to add a sending unit(fuel gauge) to the side tank of my 1975 Highboy.
I have added the the heater control tank switch & harness along with the tank solenoid & harness and have those working perfectly.
Now I want to add a fuel gauge in that second tank.
I have located within my exiting harness a green/red wire that would be the rear or midship fuel gauge..just need that last harness to the actual sending unit.
Thanks in advance
Tbruz

 

Might help even though its for a 78? I seem to remember when I deleted the side tank on my red 79 that the back wiring ended up going to a single bullet connection. But that was a long time ago. You can see a single green wire connection in the bottom pic....

 

I know this a year old thread but this should be helpful for others needing help in the future. Adapted from my recent learnings installing a D5TZ-9A050-A 5 terminal switch and wiring into my truck.

I had to take apart my instrument cluster to figure out the wiring. My in cab tank has a single orange wire with a bullet connector that was plugged into an orange double connector in the dash wiring harness that looks like the one in the picture below. Pictured below is a 3 port switch and wiring loom that I have, but it shows the orange and green - green w/red connectors quite well that are the same on the 5 port harness.


The two orange double connectors went into each other.


The single orange wire with brownish looking connector coming off the 5 port switch connected went to a reddish wire with the same style connector behind the instrument cluster. No other connector was the right style to mate up:


The brown with white stripe wire that runs all the way to the selector valve and uses a grey connector in the cab connected to a brownish looking wire on the 5 port loom (lower left wire in this pic)


Figuring out the actual tank sending unit connections was the hardest part. I looked at 73, 77 and 78 wiring diagrams. I made my in cab gas tank the main tank and the aft axle tank the aux tank. At first, my fuel gauge would only read the fuel level of the in cab tank OK but not the aux tank. I put 1/4 tank of gas in the aft axle tank but the gauge would go to empty on the aux tank. The green w/ red stripe wire goes that from the switch to the aft axle tank was a bit of a mystery as the 5 port harness has both a single and double green w/ red stripe connector that has 3 wires coming off the one side of the double connector. Once I looked at the 75 wiring diagram did it finally click for me on exactly what I needed to do. Wiring is not my favorite area but I figure it out eventually with patience and methodical troubleshooting.


From playing with the fuel gauge and switch locations I determined that the in cab tank sending unit, which is a single orange wire male bullet connector in my case, needs to be plugged into the single red female bullet connector that is a green w/ red stripe colored wire. In the pic above you can clearly see the red female bullet connector. What you cannot see is that the orange male bullet connector from the in cab tank sending unit is plugged into the red female bullet.

What I didn't know, was how to get the aft axle tank sending unit to hook up. The double connector on the 5 port harness was throwing me off. I couldn't figure out how a single wire sending unit wire would mate up to the double port connector. Once again, patience and methodical troubleshooting paid off. With 4 gallons of gas in the aft axle tank I grounded the aft axle tank end of my replacement green w/ red stripe wire that goes from the switch to the aft axle tank while connecting the in cab connector to various male and female connectors until I found the right one that caused the fuel gauge reading to go to full while the wire was grounded to the chassis with the tank switch on aux.

I had incorrectly guessed that the in cab side of the green w/ red stripe colored wire for the aft axle tank needed a male bullet connector in the cab. What is needed was a female bullet connector to connect to the male terminal half of the double port green / red stripe and green wire connector on the 5 port harness:


My 5 port tank selector valve is installed and properly registering the fuel level in each tank.