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406cid70Chevy · 05-29-2004, 09:38 PM

My truck drains the battery when it's running. So I checked the battery with a multimeter, it's at 12.8 volts with the engine off. With the engine on it's at 12.6 volts. Shouldn't it be at about 14.2 volts when the engine is running? I have the old style externally regulated alternator. Are there any tests I can perform to determine if it's the alternator, voltage regulator, or another source? Could bad grounds cause this? Thanks!

05-29-2004, 09:38 PM	#1
406cid70Chevy Registered User Join Date: Nov 2002 Posts: 43	charging system question My truck drains the battery when it's running. So I checked the battery with a multimeter, it's at 12.8 volts with the engine off. With the engine on it's at 12.6 volts. Shouldn't it be at about 14.2 volts when the engine is running? I have the old style externally regulated alternator. Are there any tests I can perform to determine if it's the alternator, voltage regulator, or another source? Could bad grounds cause this? Thanks!