I was putting some lights together tonight and when I was putting the heatshrink on I was think about ways of checking which pigtail pin was hooked up to +ve/-ve/data (ws2811 pixels) in the future as I wouldn't be able to see the soldered connections. So I thought I would check the wire resistance between pins at each end of the string to see what it told me. This is what I got. +ve in to +ve out - very little resistance (ie direct connection) +ve in to -ve out - higher resistance +ve in to data out - no connection -ve in to -ve out - low resistance -ve in to +ve out - higher resistance -ve in to data out - no connection data in to -ve out - higher resistance data in to +ve out - higher resistance data in to data out - no connection I've tested the lights and they work. I have not tested if a string connected downstream works yet as I haven't got another string with connectors on it yet. What this tells me is I can isolate the data pin from the +ve/-ve pins but I can't tell which one of the other two is +ve and -ve by using resistance measurements. If you forget the pin location is there a way of determining the +ve and -ve pigtail pins without cutting the heatshrink off and looking. I hope this makes sense and I hope the measurements I've taken are right. I've double checked but I could be going number blind.