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Kirk Morgan · 01-11-2024, 12:26 AM

Do a voltage drop test. Start the truck with nothing on and check the voltage at the alt. and the battery. It should be same. If the voltage is low you will need a inductive amp meter to see how many amps the alt. is putting out. If it putting out lets say 50 amps or more with nothing on you have a battery problem. If the voltage is low and there are no amps coming out of the alt. the alt. is bad. On some newer cars and trucks the computer is the voltage regulator. I am not familiar with you GMC how the voltage is regulated.

01-11-2024, 12:26 AM	#4
Kirk Morgan Member Join Date: Jan 2009 Posts: 195 Likes: 0 Liked 52 Times in 30 Posts	Re: Alternator problem on 2021 GMC Terrain Do a voltage drop test. Start the truck with nothing on and check the voltage at the alt. and the battery. It should be same. If the voltage is low you will need a inductive amp meter to see how many amps the alt. is putting out. If it putting out lets say 50 amps or more with nothing on you have a battery problem. If the voltage is low and there are no amps coming out of the alt. the alt. is bad. On some newer cars and trucks the computer is the voltage regulator. I am not familiar with you GMC how the voltage is regulated.