I just saw your pic. I believe you have missed something. The sending unit is a 30 ohm resistor. The resistance of the gauge is not normally checked. The resistance of the gauge, other than it is not shorted or open, is not important to us. Gauges can be built in a number of different ways. Yours most likely is the two coil type. Not to over think this lets just say it works as two electro magnets.
The Function Test is...with correct voltage and ground attached. The sender post with no connection, the needle will read either M/T or full. With the sender post shorted to ground, the reading will be reversed.
Calibration of gauge is as stated above with resistors. I use a pot (0 to 100 ohms) or variable resistor as a lot of senders are 0 to 90 ohms.
Last edited by beltfed; 07/12/2015 12:49 PM.
