820-01949 wont charge battery

[Kyle93]

Customer claims there was liquid damage but only very minor corrosion was found by C6454 . This turns on and works but refuses to charge the battery.

Replaced battery with a known good battery but no change

PPBUS_G3H is 12.60 with or without battery.

What to check next??

 

[2informaticos]

Check SYS_DETECT and SYS_DETECT_L levels.

 

[Kyle93]

SYS_DETECT_L 3.3v
SYS_DETECT 3.3v

 

[2informaticos]

If Q6955 is on the board, change it.
If not, change R6950.

 

[Kyle93]

SYS_DETECT_L is now 0v but no change.

Osx recognizes the battery but will not charge it or run off it. Service recommended message shows even on known good battery. Tried PRAM reset as well

 

[2informaticos]

Really known good battery, or new chinese supposed to be good?
What's the PPBUS_G3H and 3V3_G3H_RTC voltage with battery alone (no charger)?

 

[Kyle93]

Really known good apple original battery. No sticker with apple printing like other chinese suppose to be good.

0.850v PPBUS_G3H and 0.185v 3V3_G3H_RTC

 

[2informaticos]

SYS_DETECT_L with battery only connected?
Be sure to have good contacts for J6951 and battery screw tight.

 

[Kyle93]

After finding R7062 was blown, replaced and battery is now charging normally and runs off the battery no problem.

Stuck with the service recommended message though. Reloaded with Monterey but no change. Also tried SMC reset and PRAM reset.

What else can I try to remove the message? The same message appears with 3 different batteries on this board

 

[Kyle93]

According to coconut battery the status is good and 100% capacity.

Ran into this issue another time with a 820-00426. Ended up fixing it by trying a new bios.

In this case would T2 need to be restored to be considered new bios? Tried revive option but no change.

 

[2informaticos]

Many people complained on Internet about battery problem caused by Big Sur, or Monterey upgrade.
Save the data, do restore and reinstall original macOS.