Upgrading H4 Halogen to Philips Ultinon LED

Thought I would share my expensive journey of trying to upgrade the Prius h4 headlights to Philips LED's. Might save others wasting there $$ and time and effort. I only wanted to go with the Philips LEDs as they have a good reputation and put a lot of R&D into there products compared to the cheaper LEDs on the market. They also don't blind other drivers with there "safe beam" feature unlike other cheaper LEDs that can throw light all over the place. The Philips probably emulate a halogen filament better then any other LED available, so less likely to get in trouble and a reason for the police to pull you over.

I started with trying to fit these Gen 1 Philips ultinons.

Someone else on the forums also tried to fit these, and ultimately they just don't fit with the large passive black heatsinks fouling the headlight housing. See here for the best attempt by another forum member (I'm still not sure how they managed to get those heatsinks on even 50% of the thread! good job!)

I even tried to create my own heatsinks made from blocks aluminium carved with cooling fins and taped with the correct sized thread to screw onto the Philips LED, but they did not perform as well as the stock heatsinks due to size constraints, so deemed a failure. Here is a temperature comparison:
Stock gen1 heatsink
My DIY heatsink

So then I ordered the newest Philips Gen 3 ultinons (from Blingwork Automotive Lighting Australia for anyone curious)
Here is the Philips gen3 box
Here is what they look like close up

Unfortunately it wasn't a simple drop in installation. But its close. Just a small amount of material needs to be removed from the headlight locking ring. For this I had a spare set of headlights to test it all out with first. The installation into my actual Prius does not require you to remove the headlights from the vehicle as others have mentioned. Its a tight area to work in, but doable.

Here is what the locking ring looks like when you remove the weather proof rubber seal (it turns anti clockwise to remove from the headlight assembly for those not familiar, the rubber just peels off easily):



And here are couple shots showing the LED fouling on this plastic ring.



So with your locking ring in the locked position you can mark where the LED needs clearance, or try to gauge from my photos where to remove material. Using a rotary tool die grinder or other cutting tool its easy enough to shave out a little material from the locking ring, so the LED can drop into position.




When installing these LEDs there is not a lot of space to work with, but you can remove the fuse box cover to gain a little extra hand room on the left hand size, and the air intake plastic thing, and some of the electrical plugs off the washer bottle to gain more hand room on the right hand side.

Its pretty self explanatory when you have these LEDs in your hand, but ill try to explain how to install them anyway.

With these Philips Gen3 LEDS the H4 base twists off the LED, and you install that part into the headlight holder retention clip first. Then you install the rubber weather proof seal back onto the locking ring, and install that back into the headlight ( the ring only fits in one orientation then you turn it clockwise all the way to lock it).

finally you now insert the LED into the headlight (it rotates and locks into its H4 base.) The rubber weatherproof seal will overhang over the top of the heatsink a little bit which is not a problem, the active cooling keeps it cool running just fine. Finally you need to plug the headlight power connector to the LED lead and your done.




Final thoughts, its a worthy upgrade over the halogen bulbs for sure. I wouldn't say I was blown away at first. The light output is different then what I'm used to, i kind of liked the warm yellow light, but the visibility is not as good as these LEDS, after some time they really are superior. I don't know how they compare to the HID headlights.