Re: Tempature lamp 69 El Camino..
The temperature dummy light should come on while you are cranking the engine. This was done as a self-test of the lamp.
The first thing to check is see if the lamp itself and related circuit is good....
Turn the key to "on", disconnect the wire from the temp sender on the engine, touch the wire's connector to a good ground--the dummy light should come on.
If it lights, there is an issue with the connection to the lamp test terminal on the ignition switch.
If it doesn't light, you have a bad bulb, poor socket connection or issue elsewhere in the circuit.
The bulb has +12v at all times when the key is on or cranking via the pink wire. The ground put on the dark green wire from the under hood sender OR the lamp test function of the ignition switch complete the circuit to make it light up.
-If you don't stand for something, you'll fall for anything.