Chosen Solution
So I bought a drive caddy and an SSD for my Mac, I put the SSD in the drive bay, and moved the 1 TB drive to the caddy and replaced the optical drive. When I power the machine on, the drive appears to be functioning properly, but when I try and open it in finder it locks up on me. Disk utility seems to lock up on startup, and when It does eventually load it has problems verifying the drive. When I drag a file to it, it gives me error code 50. I figured I cheaped out on my caddy and got a faulty one. So I went and ordered the expensive OWC one. Now the drive spins up, but refuses to function beyond that. The drive functions perfectly using a USB/SATA dock, but not inside the macbook. I am at a loss here
I’m a bit confused, exactly which drive are you using for a boot drive and which drive are you having issues with. There is a known issue with this machine but it is the Hard drive/IR cable. We have been able to fix this issue by going to the 2012 cable (sometimes mods need to be made to the hold down screws, MacBook Pro 15" Unibody (Mid 2012) Hard Drive Cable
Hey there! Sorry to hear about the consistent issues. If the hard drive works well in other instances, the issue may be as simple as a poor SATA cable. The hard bend in the cable leads to high failure rate while removing the optical drive or replacing it with the new Dual drive. If you still have your original optical drive, I’d try putting it back in and seeing if you can get it to read. If your laptop is having issues with that, you probably have a cable issue. It’s a fairly cheap part at $20, and could be the answer to your problems. Other than that, I’d try cleaning the connection on your board and making sure that your current SATA cable doesn’t seem overly bent or worn. Replacement cable: MacBook Pro 15" Unibody (Mid 2009-Mid 2012) SATA SuperDrive Cable Best of luck in your future repairs!
