Thinkbook 14 G2 ITL problem with open MOSFETs.

[artenidas]

Hello,
I'm working on a USB-C powered laptop (Thinkbook 14 G2 ITL) motherboard K051P with the TPS65994 (U24) and USB-C controller (UT1, likely JHL8040R).

Here's the current status:

U24 has both 3.3V and 5V present

The EEPROM for U24 has 3.3V on pin 8

UT1 also seems fine (has 3.3V supply)

No shorts found anywhere on the board

EEPROM was flashed and soldered correctly, the .bin file is exactly 32KB, so it looks valid


🔧 The problem is:

The second MOSFET (PQS12) is not passing 20V to the output

The gate voltage is very low (~0.15–0.4V) → as if the TPS65994 is not driving it

the only thing that is still strange to me is that on UT1 there is some 3v rst line or something like that and I have 1.8v there

I already ordered replacement chips for both U24 (TPS65994) and UT1, because I’m out of ideas.

⚠️ When I inject 16.8V after the MOSFETs, the laptop boots and works perfectly, so the power path downstream is functional.

Any ideas what else could be wrong?
Thank you.

[mon2]

Your case may be the same as this one:

Lenovo E15 Gen.3 NM-D481 No starting and charging via USB-C, The device starts only via the battery. - Badcaps

[artenidas]

Only in my case, whether on battery or power supply, there's a dead zone. The PQS12 doesn't open, as if it wasn't receiving a signal from the U24 to the gateway. It only works on voltage injection on the main line 16.8v

PQS12 gate opening comes from U24 Pin E8

[artenidas]

I think I'm an idiot. My laptop has a power supply, and I'm trying to power it from a USB-C port that only has the G and V terminals from a lab power supply connected to it. That's probably why the power supply isn't communicating.

[mon2]

Not an idiot if you have figured it out. Continue to update the thread.

[artenidas]

I'll be home soon and let you know with feedback. 😁