Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
The cost to diagnose the P0AF9 GMC code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
The Engine Control Module (ECM) monitors the correlation of the generator battery disconnect control module battery voltage and the Starter Generator Control Module (SGCM) output voltage to detect a 36 volt cable open or fuse/relay failure. The ECM also monitors to detect an over voltage condition and protect the MOSFET (load dump). If either one of these conditions is detected, the appropriate Diagnostic Trouble Code (DTC) will set.
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