I have a 2022 Prius LE. I want to add an LED light which would come on when the DRL/headlight is turned on. Otherwise it should remain off. (for discussion let's ignore the new light's amps/watts). Do you have ideas of how to do this? I am able to tap into the DRL and headlight wiring to get power for the new light when they are turned on, but I'm pretty sure wiring the DRL and headlights together to the new light will cause "bad things to happen." I read somewhere about the idea of using a relay so only one source can connect power to the new light. I like the concept but I have no experience or knowledge of automotive relays. Any suggestions appreciated.
Update I can't figure out how to turn the light on "automatically" via relays. My dashboard has no empty places for a switch. I will repurpose the otherwise-unused HUD button on the multi-function switch. That goes to an MGI fused relay connected to switched power to turn the light on/off. If I ever figure out an "automatic" approach I can disconnect the switch & change the relays.
Your vehicle might already have an indicator light for DRL/headlight. In the plethora of indicators in the annunciator panel (far right third of the dashboard) there is a headlight indicator. There may be slight differences between model years and vehicle options, so I'm not certain about this feature for your model year. My Owners Manual pg.110 has the symbol and a reference page to read about it. Something else I discovered the other day. If my vehicle is made ready, in Park, with headlights set to Auto (DRL enabled) and I engage the emergency brake, the DRL and dashboard indicator light extinguish. Maybe that is how I can have what used to be called parking lights.
Gen5 LE owner here. Learning as well. My LE does not have auto on/off headlights. I liked them in my last car There is no indicator for when the drls are on. It's, like, 3 rotational steps on the stalk. I've left the drls on when I didn't want to. Of course, I've driven sans headlights until getting 'flashed' by on-coming drivers, so there's that.
I don't see what's so difficult??? I do this all the time and even chained relays together to form an if-and-or-circuit. If you can't figure it out; you should probably pay someone, before you "fry" your electrical system. - YouTube
I decided to wire it via the un-used HUD button on the multi-switch. Then I can turn it on/off when I need to. Of course that means figuring out the HUD switch and LED. The HUD button is a momentary switch so connecting it to a bi-stable latching relay turns it into an on/off switch. I'm still not sure what turns the HUD LED on/off (hoping it is not the car's computer).
You best bet is to just cut the wire and add your additional light wire to it with a buttconnector ideally, or a house type cap screw if desperate. And have the ground wire just tapped into any exposed metal of the chassis or frame. I like using a self tapper and making my own hole but to each their own. It doesnt matter where you cut the wire, i prefer somewhere easy to access and close to the day running light for convenience. Use a test light to make sure its the right wire. If its a lot of amps you are running, i would cut it closer to the fusebox because wire thickness matters and you dont want both your additional lights and day lights running off the same wire or it can potentially get too hot and melt. The fusebox fuse will pop before that however. Since its already fused, you dont have to worry about burning anything. You might pop the fuse if whatever lights you are adding is leeching too much amps from the fusebox fuse. In that case, you can install an inline fuse to each wire as precaution after the fusebox and go up in size for the original fusebox one.
