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Gary
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 15723
Experience:  15 years GM master tech
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I have a 2006 Chevrolet Silverado I change the starter and

Customer Question

I have a 2006 Chevrolet Silverado I change the starter and alternator and I still have the same problem after the truck is running for at least 20 or 25 minutes my voltage drops on my gauge on my dashboard I check the positive and negative wiring and everything is fine with a volt meter if I turn the truck off and back on it jumps back up to 14 V
Submitted: 5 months ago.
Category: Chevy
Expert:  Gary replied 5 months ago.

what does the volts drop too ?

at idle or driving at speed ?

Customer: replied 5 months ago.
The volts are dropping from 14 to around 12.8 if I turn the truck off and back on it goes back to 1420 minutes later while driving it drops
Customer: replied 5 months ago.
It does it at idling and driving
Customer: replied 5 months ago.
I have 14000 miles and I am having no physical issues with this truck I just noticed the voltage drop in on my dashboard
Expert:  Gary replied 5 months ago.

how long have you owned the truck ?

are you sure the battery's cold cranking amps and volts test good and there are no bad cells in that battery ?

Customer: replied 5 months ago.
I have owed the truck for 10 years this problem started two weeks ago I bought a brand-new battery and a brand-new alternator I actually purchased two alternators thinking the brand-new alternator from Napa was bad The battery has 12.8 V on it cold
Customer: replied 5 months ago.
On another note when I unplug the power wire leading to the alternator my voltage jumped up to 13.8
Expert:  Gary replied 5 months ago.

ok if that battery is good and tested good the computers on these trucks tell the alternator when to charge and how much too and when not to charge much at all depending on the AMPS being used and the amount of AMPS that need to go back into the battery after you start the truck up

when the alternator is unplugged it just goes into charge mode by default as the computer can no longer tell it how much to charge

the odds are there is nothing wrong at all especially with everything new and all things tested good

what you are seeing is the charging system charging when needed especially after a start to recharge the battery

as for why you just started to notice this is hard to say at this point i would not do anything more as there shouldn't be anything to fix

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

if you have any questions please ask as i do not get credit for my work until you rate me here at Justanswer

Customer: replied 5 months ago.
I guess the big question is why all of a sudden after 10 years of owning the truck the voltage is going to drop from 14 to around 13 all of a sudden
Expert:  Gary replied 5 months ago.

very hard to say why but it is charging when its being told too

that volt gauge may have just become more accurate or possibly the programming in the computer may need to be updated with current programming changes to correct the big swing of the charging and not charging

programming in the computer being updated usually will correct things like this with the updates

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

if you have any questions please ask as i do not get credit for my work until you rate me here at Justanswer

Expert:  Gary replied 4 months ago.

how are you making out ?

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

if you have any questions please ask as i do not get credit for my work until you rate me here at Justanswer