BSM Switch LED turn on

I recently installed a fake BSM (Blind Spot Monitor) switch as a stealth kill switch in my 3rd Gen Toyota Tacoma. Functionally, it works — the switch successfully engages/disengages the kill function (currently wired to the starter circuit). However, the LED indicator on the switch does not light up at all, regardless of switch position.


Here’s what I’ve done so far:

• The grey wire is grounded (confirmed, as kill function only works with this connected to black/ground).
• The red wire is receiving constant 12V (also verified).
• I’ve tried pairing the yellow, tan, green, and other wires with ground and red (12V+) — no success.
• Swapped in a known working OEM BSM switch — still no LED.
• I’m using a plug-and-play harness extension, but I’m wondering if it’s not passing through the necessary pin for LED power.
• The switch itself does not beep or light up, which it normally would with a stock setup.

I’m starting to suspect the issue is with the harness. Maybe it’s not bridging the right circuit(s) for the LED portion. I’d appreciate any help if anybody has any experience identifying:

1. Which wire controls LED power on the OEM switch.
2. How to correctly power the LED in a custom setup.
3. Whether anyone has built their own BSM extension harness successfully

Thanks in advance. Open to any advice you’ve got.

 

What LED of the OEM BSM switch are you trying to turn on and when. There are two LEDs, one for illumination and the other for activation of the BSM system. If you have just been trying everything and every combination of wires you may have burned something up. The switch contacts are only meant to present a voltage to the Master BSM module, not carry much current.

There would be no beep from the switch - the noise maker behind the left rear passenger is what beeps in the OEM configuration.

From what source did you procure the switch and wiring connector and wires? In the OEM configuration there is no red wire, but a pink one.