Chosen Solution
2011 21.5” iMac (iMac12,1) with a i7 CPU and running macOS High Sierra (10.13.6) I’m pretty stumped by this… 2 of my USB ports have stopped working, but not completely… if a flash drive is plugged in it’ll briefly light up before turning back off and not showing up at all, USB devices which need a USB port to charge work fine but no external drives or devices, and the other 2 ports still work completely fine What I’ve tried already: RestartingResetting PRAMResetting SMCChecking software updateReinstalling macOSApple hardware test (hold D at startup) running the Extended apple hardware test Please does anyone have a suggestion? thank you in advance
This sounds like you have a bad USB hub chip. Here’s a breakdown of the external ports
So as you can see there are two hubs! Ports A & C are served by Hub 1 and Ports B & D served by Hub 2. At this point you’ll need to figure out which hub circuit has failed. Both are USB Hub Controller USB2514-AEZG QFN package. Hub-1 U3500 and Hub-2 U3600 It might be a cold solder joint or the chip its self has failed.
