Here is my problem. My car's microprocessor controls the radio button illumination but not the LCD night/day brightness setting. When the parking lights turn on, it provides Pin A with 0.2 - 12 v for variable illumination level. But it doesn't provide the signal radio needs on Pin C to switch the LCD to day/night mode i.e white and black background. So, when I turn the parking lights on at night, buttons light up but LCD is always bright.
Radio dims the LCD to night mode when the Pin C circuit is open (0 volts). And switch back to day mode when it receives a positive signal. I do not know the correct current but anywhere between 0 to 12 volts worked for Pin C.
This is my solution I am using the Pin A signal for both illumination and signal for relay. When the parking lights turn on, (usually 9-10 volts) this should turn on the lights and also open the Pin C circuit. When I turn the parking lights off, remaining current on Pin A is enough to send a signal to switch the LCD back to day mode. I tested this manually and created a diagram.
Questions:
1) Is the diagram correct? I do not want to harm very expensive microprocessor and radio.
2) What diode and relay should I use? Solid state for no clicks?
3) Can I ground the relay to the radio or not?
Please help. this is my first ever project.
Radio dims the LCD to night mode when the Pin C circuit is open (0 volts). And switch back to day mode when it receives a positive signal. I do not know the correct current but anywhere between 0 to 12 volts worked for Pin C.
This is my solution I am using the Pin A signal for both illumination and signal for relay. When the parking lights turn on, (usually 9-10 volts) this should turn on the lights and also open the Pin C circuit. When I turn the parking lights off, remaining current on Pin A is enough to send a signal to switch the LCD back to day mode. I tested this manually and created a diagram.
Questions:
1) Is the diagram correct? I do not want to harm very expensive microprocessor and radio.
2) What diode and relay should I use? Solid state for no clicks?
3) Can I ground the relay to the radio or not?
Please help. this is my first ever project.
Attachments
-
25.1 KB Views: 59
Last edited: