I have the digital ambient temperature gauge accessory installed in my 245. I also have the additional interior temperature switch/sensor hooked up. For whatever reason, I can't seem to get the rocker switch to illuminate when depressed. The interior temperature switch is your typical 240 rocker switch with two spade terminals, one horizontal up top, and the second perpendicular on the side. The bulb is a two terminal bulb. The factory harness has the feed from the digital gauge going to the perpendicular side terminal and ground out from the top horizontal terminal. To illuminate the bulb I wired the switch thusly:

Brown wire from digital gauge to perpendicular side terminal.
Black ground out from top horizontal terminal to switch light bulb terminal 1.
Black ground to chassis from switch light bulb terminal 2.

For whatever reason the bulb will not illuminate when the switch is depressed. I have checked with a known working bulb, so it's not the bulb. Also, the switch is ok because when depressed the gauge does indicate a different internal temperature from the outside temp - so this should mean that the current is running through the switch, and the bulb to chassis ground.

The switch type is like the late model rear defrost or power mirror heater switch, where it only remains depressed for as long as you keep your finger on it.

Am I supposed to be drawing current for the bulb from somewhere else?

This is the last thing I need to sort out with the installation of this accessory, and I'd really like to put this one behind me. Thanks for any help.