Coolant tank was replaced only to get the coolant level sensor that is molded into the bottom of the tank. When you reset it, the temperature condition message comes on at the dash with the next key cycle, but stays off during that operation. The tank that was installed is an aftermarket tank, not OEM.
There is no low coolant or overheating happening.
How can I bypass the sensor or test the sensor?
Our info says when the coolant gets low enough, the coolant level switch opens, no continuity between the terminals at the switch. The yellow wire with black tracer is voltage to the switch from the instrument panel cluster, I believe it goes hot with the key on. The black wire at the connector is ground, just a chassis ground.
I'm not sure how much voltage is on the yellow wire with black tracer? The black ground, you can test the usual way, testlite connected to voltage, touch the terminal for the black wire, if the lite comes on, the ground wire circuit should be ok.
Check instrument panel trouble codes or any applicable codes. Some of the national brand autostores will check codes for free. I just don't know if they can check manufacturer specific codes?