Rear fog light to US Prius

Egidijus Zideckas · Nov 27, 2024

I'm in a progress to convert US Prius 2023 to comply EU requirements.
I need to add turn light signal to mirrors, this is discussed in separate thread.

Now I need to add rear Fog light. I have:

switched to EU version rear bumper (part no: 5215947950)

rear fog light (8148047030)

Switch, turn signal handle (8432912170) - this I'm not sure if it will work. So

I don't have wiring diagram to verify if US car will work with EU turn switch (with fog switch), maybe @Hammersmith could help with this?

Only one diagram which I found is mentioning FOG RR Relay:

Turn signal handle connects to Spiral Cable sub assembly - have no idea what these pin names mean.

Spiral cable then has CAN bus to whatever ECU.
So, if I'm lucky, I'll switch turn signal handle and relay FOG relay starts clicking, right?
Guess I'll have to find out

Junting · Feb 27, 2025

I am about to attempt this too as my car just arrived in Portugal, would love to hear whether you were able to get all the modifications done!

Hammersmith · Feb 28, 2025

I must have missed this before. I can't speak for the spiral cable or the turn signal switch, but just about all* Priuses come with the same Power Distribution Box Assembly. That means all the US models have the rear fog light relay.

I discovered this when doing my power folding mirror conversion. I thought my project was dead for a while because of the relays built into the PDBA until I found out almost all Priuses use the same one. That meant the relays were already there. I had to add wiring from the PDBA to the mirrors and mirror switch, but everything worked once that was done.

I don't have easy access to the European wiring diagrams, so I don't know what differences there are between the rest of the rear fog light system. It might be minor or it could be major.

*I found a second PDBA for the Prius, but I think that one is exclusive to the Japanese market and is for the very bottom trim sold there.

Junting · May 1, 2025 at 11:26 AM

So here's what I just did to get a EU legal rear fog light on my US Prius in Portugal.

Overview: I looked into all the options, did not want to buy a new EU bumper with center fog light. I decided to tap into the reverse light area, and found a Japanese aftermarket company that sold a light for around 500$ that turned the red reflectors into a light. A bit expensive, and I didn't want to wait for shipping so I made the decision to replace the rear backup light with a fog light.

Problems & Solutions:
- LR5B (Red) led was slightly different that existing L1b/LW5B (White) led. You'll see that I used zip ties to keep things secure. This is because the notches on the light are different
- LR5B led harness was impossible to find with shipping to Europe, and seems hard to find regardless. So I cut the existing LW5B harness with female connector, and filed down one side to get it to fit the LR5B led. It's pretty clear what to file down when you have the parts in hard. After that it fit perfectly snug.
- Had to extend some red/black wires because the fog harness was designed for a front battery
- I routed the wires from the switch up front all the way to the battery and LED in the back under all the plastic trim, pretty straightforward.

Next Steps:
- Right now the button is always lit because it's directly connected to the 12V battery. It's also in a position where my knee could hit it on accident and I could inadvertently part my car and drain my battery by leaving the light on. So, I'd like to wire the fog light so that there's only every power when the car is on.

Parts:
- LR5B LED from Aliexpress
- Fog light harness, any will do but I bought the one with a late-model Toyota button.
- Solder iron and electrical tape and shrink wrap and heat gun if you need to extend wires or splice cables

Pictures: