2009 Tahoe Amps Problem
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2009 Tahoe Amps Problem
I have a 2009 Tahoe 4WD LT with aprox 92K miles. I have owned for 1 1/2 years with zero issues...until now. My amp gauge has always sat well above 14. The other day I left radio on for kids while shopping for about 30 minutes or so. Vehicle wouldn't start. Battery wasn't completely dead but not enough to start. Got a jump start. There was an issue with some of the vents blowing different temp air. Using this site (thank you) I corrected the problem by unhooking positive terminal, reconnecting and all was good.
Next day I drive 10 miles and amp gauge shows normal, then drops to about 12. I park it do my errands for several hours and veh starts right up. Same issue going home. Next day veh starts right up and repeat same scenario. Take it to a parts store and have system tested. Battery showed good health but at about 60% and battery amps about about 50%.
Mechanic recommends new alternator. I install new alternator. Test drive it. No gauge issue for 20 miles plus...then exact same scenario. Back to parts store. Battery shows about 93% good health, and 100% charged. Drive 3 miles park it. Next morning straight to parts store of 3 miles and gauge is doing same crap. Test shows alternator putting out over 12.9amps, good battery health, but about 75% charge. Also, when the gauge shows 12, I can turn veh off, immediately restart it and it is showing 14+. As I drive it, it will drop, then go back up and drop.
What is the issue? Nobody seems to know. Most think the battery is testing good, but think the battery should be replaced. Others think a ground or short. The vehicle starts with easy, but the amp gauge goes back and forth between 12 and 15. There haven't been any check engine lights or codes appearing.
Thoughts anyone?????
Next day I drive 10 miles and amp gauge shows normal, then drops to about 12. I park it do my errands for several hours and veh starts right up. Same issue going home. Next day veh starts right up and repeat same scenario. Take it to a parts store and have system tested. Battery showed good health but at about 60% and battery amps about about 50%.
Mechanic recommends new alternator. I install new alternator. Test drive it. No gauge issue for 20 miles plus...then exact same scenario. Back to parts store. Battery shows about 93% good health, and 100% charged. Drive 3 miles park it. Next morning straight to parts store of 3 miles and gauge is doing same crap. Test shows alternator putting out over 12.9amps, good battery health, but about 75% charge. Also, when the gauge shows 12, I can turn veh off, immediately restart it and it is showing 14+. As I drive it, it will drop, then go back up and drop.
What is the issue? Nobody seems to know. Most think the battery is testing good, but think the battery should be replaced. Others think a ground or short. The vehicle starts with easy, but the amp gauge goes back and forth between 12 and 15. There haven't been any check engine lights or codes appearing.
Thoughts anyone?????
Last edited by titan; Mar 31, 2016 at 10:13 AM.
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the gauge is voltmeter not an amp gauge.
depending of charging mode, the ecm controlled alternator will vary the voltage and amp output. when there is a battery problem the vehicle will go into load shedding mode. the battery needs to be ruled out first before testing the charging system.
tested the battery with a conductance tester. if the battery passes, you should check charging system output. You will need to start the engine, bring it up top 2500 rpm and maintain this while the electrically system is loaded...then measure voltage and amperage.
depending of charging mode, the ecm controlled alternator will vary the voltage and amp output. when there is a battery problem the vehicle will go into load shedding mode. the battery needs to be ruled out first before testing the charging system.
tested the battery with a conductance tester. if the battery passes, you should check charging system output. You will need to start the engine, bring it up top 2500 rpm and maintain this while the electrically system is loaded...then measure voltage and amperage.