I am having trouble getting the heat warning indicator to work on my panel. There seam to be one cable missing since the are two connectors on the lamp in the panel but only one cable connected.
I can see from the oil and alternator lamps that there is one white cable (+) connected and then one two colored cable (-).

On the heat indicator lamp i only have a two colored cable at the moment connected. I used the multimeter on the cable that is connected and it did not show anything, i assume the it is suppose to send -, could it be so that the sender is broken?or to i need to have the engine running for it to work

I have tried to search for a wiring diagram but no been able to find what i am looking for.

Grateful for answers