[A Rare 70]

I have a 70 GTO that does NOT have gauges, it has the idiot lights. My temp light has never been hooked up since the previous owner snipped the wires and installed a mechanical gauge instead. I have now installed a new wiring harness and am hooking the sending unit back up. My question is when should the light come on? When turning the key to the on position the oil and volt light illuminate but not the temp light, is this correct? The bulb is good. Does this light only come on when the engine overheats? Any help would be appreciated so that I know it is functioning correctly. Thanks.

[steve v]

IIRC it comes on as a test when the ignition switch is in the cranking (starting) position.

[A Rare 70]

That's what I was curious of. Have not yet cranked the motor over, will be doing that today.

[Peter Serio]

The temperature overheat warning lamp is powered on one side (battery +) thru a 10 or 15 amp fuse when you first turn the key on, but it does not light. The low oil pressure & the gen warning light bulbs should light up. When you crank the starter over the oil pressure and gen lights go out but the temperature overheat light should light up for as long as your starter is engaged.

There is a fork or branch in the dark green wire underneath the dash (in addition to the one that runs out to the engine temperature switch) that goes over to the ignition switch. When you turn the key all the way to the right that dark green wire is grounded on a separate tab inside of the ignition switch which allows that 1 bulb to light up.

That lets you know you that just in case your car should ever overheat the red light in your dash does indeed work.

[A Rare 70]

Peter, thanks very much for the information! That is exactly what I was looking for. Randy