I changed my turn signals to LED light bars the other day. They are completely legal, but the issue I'm having is I can't use my parking lights and turn signals. The bulb that I took out and replaced with the light bar had two filaments, I want the turn signal to work as follows: When the parking lights are on and I apply the right turn signal, I want the right light bar to flash while the left one stays on. And Vise Versa. Except when I do this now the light bar dims a very small amount while the parking light and the turn signal is applied. My Question would be, what do I need to do to get the light bar instead of dimming a little bit to turn off and on while my parking lights are on. I'm not sure if this little explanation made sense, but you can ask if you need more info. Thanks!
closed as off-topic by brhans, Transistor, Marcus Müller, winny, Finbarr Jan 8 at 16:17
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – brhans, winny, Finbarr
This can be done with three relays, single-pole, changeover type.
Figure 1. Parking light and turn signals.
How it works:
- With parking lights off the blue wire is energised. If either turn signal is switched on RLY2 or 3 will click on and off illuminating the lightbar on that side when the normally open (NO) contact is closed.
- With parking lights on the orange wire is energised. Both lightbars will turn on. If either turn signal is switched on RLY2 or 3 will click on and off disconnecting the lightbar on that side when the normally closed (NC) contact is opened.
Figure 2. Timing diagram.
Note: It is important that the turn signal changes state immediately the switch is moved. This avoids the half-second or so delay that would occur if the turn signal logic is not inverted when the lights are on. This design achieves that requirement. 0.5 s at 72 kph is a travelling distance of 10 m when one car is stationary and 20 m if both are moving towards each other at that speed. That half-second can make a big difference in avoiding a crash.