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820-02020 (A2338 - MacBook Pro M1) - Battery not recognized / No keyboard backlight

HeyWatchOutDude

HeyWatchOutDude

Member
Hi,

I have a MacBook Pro M1 which doesn't recognize the battery (0% - Cross Icon).

PPVBAT_AON (with charger and battery connected) = 11.96V
PPVBAT_AON (without charger and battery connected) = 1.4V
PPVBAT_AON_CHRG_REG = 11.96V
PPDCIN_AON_CHRG_R = 20V

I assume the board is fine because both MOSFETs (Q5230/40) are testing good.

Note:
- I can successfully boot into macOS (fan is going high due of the not detected battery).
- At the first boot it crashes and then boots again into the OS.
- Sadly I don't have another battery for testing .... :/
- No battery information available under "System Report" (Cell version, hardware version, firmware etc.)
- Battery voltage (+/-) is 2.1V, pretty low.

Battery board (820-00392-A):
- Two PINs (red arrow) are connected to each pad of the flex, is that normal? (at least I measured "continuity" with the multimeter)
(Check attachment)
 

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HeyWatchOutDude

HeyWatchOutDude

Member
Same voltage.

If I need to replace the battery ... which do you recommend? (Location: Europe)

Note: The battery board was a little bit corroded at F400 area. (Fuse is OK)

Edit: Why is the keyboard backlight not working?
 
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2informaticos

2informaticos

Administrator
Staff member
Check if ALS works properly.
If not, KB backlight is disabled.

No idea where can you buy good batteries in your area...
 
HeyWatchOutDude

HeyWatchOutDude

Member
ALS is working and KB backlight can be adjusted via OS (but can't say anything on the keyboard - have tested it in a dark area)

I have found out that "RT046" was blown, replaced it now I have 5.1V on "PPVOUT_KBDLED" - still no backlight. (KB brightness is set to 100%)

Bad keyboard backlight?
 
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2informaticos

2informaticos

Administrator
Staff member
RT046 should got burnt because of KB backlight.
Test with known good one.
Be sure DP900 is not shorted A-K first.
 
HeyWatchOutDude

HeyWatchOutDude

Member
I have replaced the kb backlight and battery sadly ... both are still not working … any idea, what else I can check?

Edit: DP900 is fine.

Edit2: I noticed when turning on the MBP after 2-3 seconds it crashes and then it boots up again. (I can login etc.)
Still strange why it is crashing at the start up.
 
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HeyWatchOutDude

HeyWatchOutDude

Member
it always ends with:
https://imgur.com/a/0phmPas

edit: Now I was able to restore (repair) it but the issues like high fan speed, no battery detected and no ob backlight is still present.

What else could be the issue? I mean I have successfully restored the device.

edit2: I found the reason why the battery is not detected … shame on me that I haven’t that checked first.

https://imgur.com/a/bRBbQxD

I will order a new cable.
 
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HeyWatchOutDude

HeyWatchOutDude

Member
New cable installed ... battery is now detected and im able to charge it.

Still don't know why the KB isn't working, any idea?

PPVOUT_S0_KBDLED_CONN = 5.1V
BKLT_PWM_KEYB_3V3 = 0V
PP3V3_S2 = 3.3V
PP1V25_S2 = 1.25V
KBD_BKLT_PWM = 0V

(I have set it in macOS to max. brightness)

So the MacBook does recognize the kb backlight because otherwise I wouldn't see the "brightness" control.
Is the PWM signal required to adjust the brightness? (Gets generated from the M1?)

Edit: Fixed UP900 was bad, KB backlight is now working.
 
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