That's why I said 'diode' and not 'LED MODULE'. There is a BIG difference. HUGE in my world of electronics. Show me the schematic and parts list for the 'LED module', if you can. An LED module, if AC power will contain a LOT of parts to converts 120 AC into the 3.4V DC V, 15ma to turn on a white LED. Any DC powered LED 'light' could easily and cheaply have FWB inside to make it 'idiot proof' to install as it's not polarity sensitive.
While some consider this semantics, nit picking, or 'you should know what I mean', accurate information about a device is critical to understand 'how it works' or why it doesn't.
I run into this problem daily, guys asking me 'my code doesn't work, I get the wrong reading,etc. about a 'sensor' when really it's a 'module' they're using. 99.44% of the time they're using a prebuilt 'module' and NOT the raw sensor. One guy wanted to know why his microcomputer didn't work at -40*C, when he finally posted which device he was using , it was easy. He had the commercial rated device when he needed the milspec version.