Connecting 2009 G5 to a 2012 cMacBook Pro to use the G5 in target display mode - NOT WORKING! HELP!

Target Display Mode only works with 27" late 2009 iMacs. If your iMac is a 2009, it MUST be a late 2009 and a 27" model. The graphic you posted has incorrect information on it.

By the way, your 2009 is not a G5, the last G5 were made in 2005 which was pre-Intel based iMacs.

And according to Apple's own search using my serial number, my iMac is an "early 2009". I can assure you that it is a 24".

iMac (24-inch, Early 2009) is NOT compatible with Target Display Mode. Only certain iMac (27-inch, Early 2009) and 2010 versions are.

Apple recently updated that support article and added "24-inch" after years of being "27-inch" only. This to us appears to be a system error as 24-inch models never worked with Target Display Mode.

Cheers,

Jack

Please CAREFULLY read Target Display Mode (Target Display Mode) , the iMac must be a late 27" model and the MBP much be running 10.13.6 or earlier to work.