820-00165 - Green light, sometimes boots, sometimes just fan spin

I have a weird one. This one shows a full short on PPbus_g3h while simultaneously showing 8.6V. How is that possible?
I've triple checked this, am I going crazy?

Signs of water on the underside of the board. there was corrosion around u3210, u3220 and u7101. I've rebuilt those areas and they look great now. Also has backlight when it does power on. When it's on it recognises and charges the battery

When the machine decides to play dead, SMC bypass will just turn on the fan, then back off and it'll repeat this over and over. This indicates ISL 6259 to me but I have checked resistance on pins 17/18 = 4 ohms and 27/28 = 20ohms.

When the macbook is fully funnctional, everything works. no loud fan spin etc so good sensors
 

2informaticos

Administrator
Staff member
On the boards affected by corrosion, always better to reball SMC.

"full short on PPbus_g3h while simultaneously showing 8.6V"
Did you remove charger and battery, when measure diode mode?
Also allow 10-20s after power is removed.
And wait 4-5s with DMM connected in diode mode, as the big caps need time to charge/discharge on this mode.
 
Thanks for your reply. the second time I measued after replacing ISL i was mistaken. not actually short anymore and it's fuly fucntional now. thank you!!
 
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