Temp & fuel gauges - what am I overlooking?

Uncle Bob said

I didn't take time to solder or assemble anything - just clipped one of the pots onto a gauge pin and to ground, and twisted the knob. Both gauges went back and forth and stopped in the middle as I turned the knob. I didn't have the DVM in the circuit so I can't say what the range is, but they definitely respond to changes in resistance. I'll see about soldering the pots together and putting them in a project box tomorrow. With fewer alligator clips I will be able to get the DVM in the circuit and try to measure it more precisely.

Click to expand...

I put it all together again on the bench - actually on a table next to the car.

I connected the pin output to one side of a 100 ohm pot and grounded the other side

I also connected my DVM into the resistor circuit.
When the cluster was powered the DVM read 1. (open), so, I would sneak up on the adjustment and watch the gauge. Once the needle got where I wanted it and stopped moving, I powered the cluster off (removed ground), and read the ohms from the DVM.

Readings from the fuel gauge

E = 40
1/4 = 30
1/2 = 18
3/4 = 13
F = 11

I ran out of time but I will see about getting that to repeat later, maybe with a different pot.

I will also note the numbers from post #3 (74, 23, 10), adjust the pot to that resistance, then see where the gauge goes.