Car blinker setup, turning off parking lights when blinker signal is high
From your schematic, it looks like you are trying to construct a basic inverter. I would suggest something like this instead:







simulate this circuit &ndash; Schematic created using CircuitLab

The portion within the red box is a typical CMOS inverter. I wouldn't recommend using the 3 MΩ resistor pull-up shown in your schematic.

The input to the inverter is your blinker signal. Here I'm using an SPDT switch to highlight the fact that you must be sure that the relay switches between a high level (+12V) and ground (or a pull-down to ground). In other words, make sure that your relay isn't floating when the relay is not active.

The output of the inverter then goes to a driver for your LED. The Zener acts as a simple regulator to protect against voltage spikes.

You'll have to play with R1 to satisfy the requirements of your LED (light).