Battery light on dash, bad grounds?

[Kilkorle]

Hello, I have a 2008 Ford Expedition XLT and the battery light is coming on in the dash, a friend at napa checked the alt/bat and said they are working just fine, he ran codes and said he thinks a ground wire is not connected good by the codes he was seeing (high voltage, low voltage) , I'm not experiencing any problems other than the battery light beeping at me every once in awhile and staying on, any ideas where I need to look for the grounds? Thank you

 

[99WhiteC5Coupe]

Hello, I have a 2008 Ford Expedition XLT and the battery light is coming on in the dash, a friend at napa checked the alt/bat and said they are working just fine, he ran codes and said he thinks a ground wire is not connected good by the codes he was seeing (high voltage, low voltage) , I'm not experiencing any problems other than the battery light beeping at me every once in awhile and staying on, any ideas where I need to look for the grounds? Thank you

Check and clean if needed the battery terminal posts and connectors. Use a battery terminal brush tool.

Follow and clean the end(s) of the negative battery cable.

 

[DieselMonk]

It can’t be the enginge ground strap, because otherwise you wouldn’t be able to start it.
Borrow a multimeter from someone, start the car and measure the voltage directly across the battery lead posts.

 

[99WhiteC5Coupe]

Hello, I have a 2008 Ford Expedition XLT and the battery light is coming on in the dash, a friend at napa checked the alt/bat and said they are working just fine, he ran codes and said he thinks a ground wire is not connected good by the codes he was seeing (high voltage, low voltage) , I'm not experiencing any problems other than the battery light beeping at me every once in awhile and staying on, any ideas where I need to look for the grounds? Thank you

What stored trouble code(s) were present?