I bought a 1989 f350 dually a few weeks back. It has the 7.3 idi with a banks turbo and a manual swap. When I bought it the dash didn’t work at all. The lights came on but the gauges didnt work at all. The guy I bought it from said it was because it was manual swapped but still had the automatic dash. He also had to put a remote switch for the starter so you turn the key to turn everything on and then flip a switch to engage the starter and get it started. Well yesterday I went to start it and the switch didn’t work. After some trouble shooting I jumped the ignition relay and it started right up. Then I got in the cab and the rpm gauge and check engine light worked. The other stuff on the dash like the gas gauge, oil pressure gauge and coolant temp gauge still don’t work. All though the coolant and oil did move to 0 which has never happened before. Also my alternator didn’t work before but now I think it is because the battery gauge went up. Any idea what could be my problem?

 

Not sure what the problem is, but I did this same swap from a c6 to a zf 5 speed and my dash works fine. When I did my swap I had a donor, and found there was a green plug below the brake booster that went to all the transmission and transfer case wiring. I went to the zf donor and it had the same plug. I unplugged that harness from the donor and plugged it into my truck after taking the automatic harness out, and it was plug and play, everything worked.

I did notice for the starting, the automatic harness had two red/blue stripe wires both going to a neutral safety switch. Of course the zf did not have a neutral safety, and I looked in the zf harness and you could see where the factory took these two wires and jumped them together. If you found this transmission harness on your truck, and found the two red/blue wires that used to go to the automatic, and tied these two together, I bet it would start.

Your other problems are something else previous owner messed up. I personally would not worry about the temp and oil gauges, the oil pressure gauge in 1989 was a fake gauge from the factory. They used a pressure switch and a resistor make the gauge read in the middle of the scale. If you have at least 5lbs or greater oil pressure, the gauge always reads in the middle. If you have less than 5lbs, the gauge will go to zero. The temp gauge is not much better telling you what is "normal". What is "normal"? Any Ford car or truck I care about I put aftermarket gauges on them with real numbers.

There are some tests you can do for the fuel gauge. But if you have a trip odometer and your speedometer works, that can be way more accurate than a fuel gauge.

 

check the ignition switch. they like to split open between the metal and plastic parts.