Powering IOT Guage and Pressure Sensor

I tried adding a terminal connection on the Gauge and Pressure Sensor, but having trouble with powering it with that.

My multimeter shows 12V over the two terminals I added.

In either switch position I don’t receive any transmissions.

If I add the batteries back in, and flip the switch, I receive transmissions.

Are there any other test points I can check with my multimeter?

Is the terminal I attached in the wrong spot perhaps?

Is there another spot I can use for powering this sensor?

in the product line we have to add an extra power circuit in order to support external power supply.

the extra power circuit gets installed in the 3 holes near CB marking.

we can send you a couple of the power supply boards if you are planning to use with external power supply.