11 Yukon XL Denali Electrical Issue P0621 SOLVED

[mikez71]

Awesome!

I wonder how the throttle sweep cleared it up...
Maybe dirty contacts in throttle actuator got wiped?
(unless it was the battery, but it tested good and voltage looked steady...)

I'm guessing the AFM codes existed when it got disabled..
And will never clear since the ECM doesn't run the checks anymore..
Flashing the ECM should fix it, but then would need programming again before driving.

Either way, nice find!
And thanks for the update and solution!

 

[Joseph Garcia]

I'm glad to read that your issue is resolved. Please add the word "FIXED" or "SOLVED" to your thread's title, to let others who are experiencing a similar issue know that this thread has an identified solution.

 

[dmax007]

THANK YOU @SpareParts and @mikez71 and community! @mikez71 got me thinking about it not being a battery issue and more of throttle body/acc petal issue. @SpareParts got me to stop thinking about history codes and electrical issues. When I stopped focusing on electrical I believe I figured it out.
2 weeks ago it was idling rough and I cleaned the tb. I bought this scanner to relearn idle and it was still messed up. Then I stopped driving it and started messing with electrical. That’s when I got the charging issue message.
Last night I fully charged the battery on trickle charger, put it on and decided to do a throttle sweep which changed my actuator on the tb voltage to normal. It’s idling good for my test drive and has the power I remember.
Thank you everyone for all the suggestions it really helped me.

I have been having the same problem. Ever sense midas did a throttle body relearn the Idle fluctuates when in gear and parked. Now im getting the service charging system like you had. Could you tell me how you did the throttle sweep?