820-3437 Missing SMC_SENSOR_PWR_EN

[mdc2018]

Machine gets orange light, no fan spin.

Found it was missing PP3V3_S4SW_SNS.

I tracked this back to U8050 and found that U8050 was not getting SMC_SENSOR_PWR_EN.

I found that the SMC Creates the SMC_SENSOR_PWR_EN signal.

I changed this SMC and still have the exact same issue, nothing has changed.

Any Idea?

 

[2informaticos]

That signal appears later.
Did you check first signals from the power on sequence?
Try to start in SMC bypass, if you think about sensors error...

 

[mdc2018]

How do I perform an SMC bypass, image assuming it is different than an SMC reset?

And yes ,I worked my way down power rails everything appeared to be present until I hit PP3V3_S4SW_SNS

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[2informaticos]

Press power button, connect MagSafe and keep pressing 5-10s...