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GM Bob
GM Bob, ASE Master Technician
Category: GMC
Satisfied Customers: 963
Experience:  30 plus years experience as GM technician, ASE Master Technician and GM Certified
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While driving the charging gauge will drop from 14.2 to 12 v

Customer Question

While driving the charging gauge will drop from 14.2 to 12 v and jump back and forth .iv been told that's ok but I know that's not true it didn't happen for the first 8 months what should I do
JA: What is the model of your '14 GMC?
Customer: 2015 sierra
JA: Are you fixing your Sierra yourself? What have you tried so far?
Customer: No its gone to dealers
JA: Anything else you want the mechanic to know before I connect you?
Customer: I've had other electrical problems but I'll deal with those later
Submitted: 14 days ago.
Category: GMC
Expert:  GM Bob replied 14 days ago.

Hello my name is Bob

The system as several modes. This is a common complaint on GM trucks.

Sorry to let you know it is normal.

Here is a link on how the charging system works.

Half why down the page is Charge Mod / Fuel Economy Mode.

Hopeful this will help.

https://www.dropbox.com/s/qzyygm5yf5y95ti/2016%20charging.pdf?dl=0

Please let me know if you have more questions

Expert:  GM Bob replied 12 days ago.

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Expert:  GM Bob replied 11 days ago.

If you can take a moment and rate my service.

Thank you