The terminals on the back of the gas gauge are marked “A,” “S,” and “I.” Test it with the “I” and “S” terminals.
2 D cell batteries should show 1/2 of full reading, 3 D cells near 100%
That doesn't apply to the 3 post gauges. "I" is input for all. "S" is sender for all.
"I" / Input for this 3 post fuel gauge is 12 volts. "A" is altered/adjusted so "A" and "I" are the gauge posts.
