Service Battery Charging System

[Eric De Carteret]

So, My 2009 Yukon Denali throws the "service battery charging system" message on a daily basis. The little red battery light comes on as well and stays on for varying times. The message seems to only come on while the truck is idling or moving at slow speeds (like when I drive down my muddy driveway or stopped at a light). The battery light may be displayed anywhere between 10 seconds to 30 minutes. Performance of the truck doesn't seem to be hurt in any way however the voltage gauge doesn't stay super consistent while driving. I had the old battery checked and replaced shortly after I bought the truck a couple of months back since it had trouble starting. Other daily symptoms include flickering lights and screens while at idle. Yes, the battery cables are corrosion free and securely attached to the battery itself.

Anyone else experience or have a solution to this issue?

Thanks!

-Eric

 

[97audia4]

Have you checked the alternator ?

 

[Eric De Carteret]

Have you checked the alternator ?

I havent checked the alternator itself however the gauge cluster in the truck shows the voltage between 13 and 15 volts while driving. So it must be doing something right, right?

 

[ivin74]

Check the positive wire and the fuse link to the alternator. Make sure its making good contact.

 

[swathdiver]

Seems to me your alternator is having trouble providing electricity at low rpms.

 

[Kraig]

Two suggestions that may or may not solve your problem, but I think they’re good suggestions nonetheless:
First, do the Big3 mod. It’s just a good idea and thwarts ground problems before they present themselves.
Second, disconnect the connector on the little box clamped onto your negative battery cable. You’ll lose approximately .01 mpg but your battery gauge will read right in the middle all the time because the alternator is not being throttled to eek out that last little bit of mpg.

 

[thompsoj22]

08 denali xl 6.2 had a similar problem but when the "service bat charge sys" and "red light" illuminated the volt gauge was stable and low. It was the regulator in the alternator failing. I replaced the alternator with a napa premium reman and also replaced the RVC module that is attached to the bat tray and the ground cable runs through it. The vehicle has had no issues since. These vehicles IMO struggle in the summer time with the huge loads from dual ac/cooling fans at idle. Add to that the RVC will turn down the charge voltage when it senses high bat temps and than when the bat drops in voltage the RVC system will crank the alt back to max output to bring it back to charged parameters. I could go on and on about the system, it does work and i have left it intact, i also install a overdrive pulley on the alt for the summer months to compensate for the extended idleing and dual ac on max that we experience here in the ca desert. you are brave to drive it like that, if the voltage is low eventually it will crap out on you.

 

[Eric De Carteret]

Thanks for the insight, gang! I'm going to get the alternator tested soon hopefully and dive in deeper if need be. I'll keep y'all posted.