I need to replace a motor on my Air 2S after a hard crash bent the shaft. Got a replacement motor but it has three wires while the original motor connects to a four-wire harness from the ESC board. The replacement motor specs match perfectly (2312S brushless) but I'm confused about the wiring. How do I properly connect a 3-wire brushless motor to the 4-wire ESC connector? The fourth wire on the ESC harness is thinner - could this be a tachometer feedback wire?

I've checked continuity on all motor windings and they test normal at 12.8? between phases. Don't want to fry the ESC by wiring this incorrectly.

The fourth wire is likely ESC feedback or temperature monitoring - you can usually leave it disconnected as most motors work fine without it. Make sure you match the three main power wires correctly by testing motor direction after installation.

I ran into the same issue with my Phantom 4 Pro! Just connect the three motor wires to any three of the ESC wires and test spin direction - if it's wrong, swap any two wires to correct it. The fourth wire can be capped off safely.

Be very careful with motor replacements on newer DJI models. Make sure you get the correct V2.0 ESC-compatible motor, and put your old motor back in first to test if the ESC is actually working before assuming the motor is bad.