820-00138 High Fan

[wasaab]

Hey everyone, so I have a 2015 820-00138 MacBook Pro in for repair that has been really been a pain. I replaced U7100 after a voltage rail issue from a water spill. Now the laptop turns on and runs, but fans ramp up to 100%. I can boot to the OS and ran Mac fan control and all temp sensors seem to be reporting correct. I sprayed each one with freeze spray and can verify the change to them. I replaced the FET that controls the fans with a known good one with no change. All temp sensors have continuity. I also removed the SMC and re-balled it and put it back on with no change in fan behavior. Board is running with bare minimum just both fans, no trackpad cable, no camera cable just to rule those out as possibilities, I also disconnected the RIO connector with no success. Hoping someone may have some insight in where to look next. Thanks in advance!

[mayss]

There is a temperature sensor in the trackpad. You must have a working cable without corrosion connected. Do ASD tests and see which sensors it reports.

[wasaab]

Thank you @mayss. Now that you say that I took a closer look at the trackpad. I replaced the top case of this computer with a refurbished one and looks like some of the components were knocked off the trackpad board by the refurbisher. This may explain the issue. I will have to get another trackpad and test this out again to make sure fans return to normal again. Unbelievable, I was trying everything and diving way too deep on this! Need to start with the simple things first. Thank you!

[wasaab]

@Mayss so sure enough you were right on the money, swapped the trackpad out and now fans are back to normal, thank you for the assist on this one! I hadn't looked close enough at the trackpad until you mentioned this.