Yesterday, 10:17 AM
So I have a 2020 XC40 T5 Momentum with a sunroof. Unfortunately the car has no rear passenger lights (absurd, I know), and it makes it very hard to strap kids seatbelts in the dark, etc. I started searching for the lights and finally sourced them, cut the headliner holes to install them and...found no wiring for the lights underneath 
Just wondering if anyone has had experience retrofitting these and had to fight the same battle. A few observations/guesses I have this far:
1. Looking at headliner options on eBay I see the headliner wiring loom is one big piece and connects to a lot more things than just the lights, so I'd rather not dismantle/replace the entire headliner or its wiring.
2. If anyone has an idea how these work please share. I assume some CANBUS signal is involved, the light fixtures seem to have ambient light LED as well. The lights connector has 3 pins, so it's either digital signal or just separate wires for ambient and normal lights, yet it makes no sense as the light has to go on when the door is one OR be powered on manually by pressing the button.
3. I started to wonder whether I could tap into the front light fixture and get power and signal from there. When I opened the front light fixture (the one that also has the On-Call and SOS buttons on it) I found two things (attaching a picture below for reference):
a. A free green connector with 3 wires which was taped to the rest of the wiring. When measured with a multimeter it seemed to have some constant 12v between 2 of the wires, and then some varying signal on the third. As it fit perfectly into the light fixture I could not resist trying it out. Unfortunately it did not work - no light when opening the door or pressing the button. Wondering what this connector might be for? I then thought it's possibly a software feature, so I changed the interior lightning item in the car config form mid to high level illumination (no RGB), but still the same results.
b. The connector that goes into this front light fixture is badass - big white connector with lots of wires going into it, which I've no idea about. I could potentially trace which ones go to the actual light module, but it seems to have some internal wiring (all black wires), and might not be so straightforward, especially if my CANBUS signal theory is right.
TIA everyone!
Just wondering if anyone has had experience retrofitting these and had to fight the same battle. A few observations/guesses I have this far:
1. Looking at headliner options on eBay I see the headliner wiring loom is one big piece and connects to a lot more things than just the lights, so I'd rather not dismantle/replace the entire headliner or its wiring.
2. If anyone has an idea how these work please share. I assume some CANBUS signal is involved, the light fixtures seem to have ambient light LED as well. The lights connector has 3 pins, so it's either digital signal or just separate wires for ambient and normal lights, yet it makes no sense as the light has to go on when the door is one OR be powered on manually by pressing the button.
3. I started to wonder whether I could tap into the front light fixture and get power and signal from there. When I opened the front light fixture (the one that also has the On-Call and SOS buttons on it) I found two things (attaching a picture below for reference):
a. A free green connector with 3 wires which was taped to the rest of the wiring. When measured with a multimeter it seemed to have some constant 12v between 2 of the wires, and then some varying signal on the third. As it fit perfectly into the light fixture I could not resist trying it out. Unfortunately it did not work - no light when opening the door or pressing the button. Wondering what this connector might be for? I then thought it's possibly a software feature, so I changed the interior lightning item in the car config form mid to high level illumination (no RGB), but still the same results.
b. The connector that goes into this front light fixture is badass - big white connector with lots of wires going into it, which I've no idea about. I could potentially trace which ones go to the actual light module, but it seems to have some internal wiring (all black wires), and might not be so straightforward, especially if my CANBUS signal theory is right.
TIA everyone!
