Seems electrical. ( bad ground somewhere ? Showing PO205 )

P0205 GMC - Injector 5 Control Circuit... Possible causes; Faulty fuel injector 5, Fuel Injector 5 harness is open or shorted, Fuel injector 5 circuit poor electrical connection......First off, the scanner you used must not be capable of reading ABS codes or you would have mentioned it. Reading the ABS code saves time, it would tell you what wheel to look at. Most common problem with a ABS code is a bad wire. The po205, chances are it would be a bad wire, but I would replace the injector also. You would need a digital volt ohm meter for checking the wires. Start at the plugin and check back into the wire from the injector for continuity of the wire. Chances are it is right at the plugin.