How To Install LED DRLs on Your Gen2 Prius

I've been wanting to do this for awhile, but never found the right lights. I just happened to be browsing a website someone told me about and found some really inexpensive, new technology COB LEDs and decided to order a few based on the reviews, one of which said "they're so bright you can't look directly at them". I thought it was hyperbole until they showed up at my house (only a week later directly from China!), and they weren't kidding!


These lights are very thin, and there's an aluminum bezel, but it just protects the edges and is useless for mounting, so they come with double-sided adhesive tape. The first thing I did was put one in my cargo area in parallel with the little "trunk light". Somehow I blocked the switch on the trunk light so it no longer turns on, but that's OK because you could barely see it anyway. Now my wife complains that it blinds her...go figure!

Anyway, the first thing I did was put some silicone on the wires as a strain relief, because they are very thin 24 gauge. Then I had to buy 8' of 1/2" aluminum angle at Lowes and some serious Scotch Ultimate double-sided tape that was rated as waterproof (or at least outdoor-capable). I did all the mounting stuff and attached them to the highest louver on the lower grille, and finished up with some cable ties, because I'm a belt-and-suspenders kinda guy.


The tricky part was figuring out how to wire everything. After perusing everything useful on the net (85% of which was here on PriusChat), I decided to keep it real simple and do hookups in only one spot. The easiest thing to get to was the little relay box under the middle of the windshield, and it comes off easily with two 10mm bolts. Cut the cable tie where it comes into the box, and carefully pry the back off. Now you can get to the wires themselves.

You only need two connections here. One goes to the purple wire (it's marked violet in the actual wiring diagrams) on either the PTC HTR1 or PTC HTR2 relay (they both go to the same point, and it provides +12 volts when the Prius is in READY mode). The other goes to the brown wire on the fog light relay, and that goes to +12 volts when any lights (running, low beam, high beam) are on. So I used an SPDT relay for the simple "logic" necessary to turn off the DRLs when the lights are on, per US guidelines.

I used a fuse coming off the relay to the DRLs, and a ground wire to the engine just a few inches away. I enlarged the mounting hole on the relay and mounted it right to one of the relay box bolts.



Hopefully the photos and schematic will explain the rest. Any questions, please ask away!

 

Thank you sir/madam! And since I see you're from the Boston area...hope you have snow tires!

 

Actually, I'm in California, but we're having torrential rains and wind right now so I'm not leaving the garage anyway! I know about Mass. because I have a friend there near Framingham who's seriously snowed in.

I plan to post updated pics if/when the sun comes back.

 

Never use automatic car washes, but I did take a good look at the edges of the circuit board, because I was sure that "cheap LEDs from China", even if claimed waterproof, were going to need more sealing. I was pleasantly surprised to see that they appeared to be quite well molded and sealed already. If they fail, I'll certainly post about it.

 

Anyone here from Roseville, California? I passed through there a week or so ago and saw someone driving with these same LEDs!

Mine are still going strong, BTW.