820-00239 Touch does not work

[iClub]

This mac has a bubble on Flat J4402, I replaced the Topcase along with touch bar, in testing it worked, but then it stopped. I replaced the Q4400, but it didn't work. The LCD in the Bar Works.

 

[2informaticos]

Check voltage on pins 20, 21, 22.
Do you get login to macOS, or critical update error comes up?

 

[iClub]

J4402	Voltage	Diode
20	2,99	0,412
21	2,99	0,411
22	5,13	0,451

No critical software error occurs.

 

[2informaticos]

So you get backlight on touchbar, but no image, nor reaction to touch on it?

Did you test with another known good touchbar?

 

[iClub]

So you get backlight on touchbar, but no image, nor reaction to touch on it?

Exactly.
I tested it with two Topcases and it works perfectly.
Shouldn't it be 1.8V on pin 20/21? I am testing with the Flat touch disconnected and the LCD of the BAR connected.

 

[2informaticos]

Check U4404 for I/O short.

"I tested it with two Topcases and it works perfectly."
Works correctly what, the main board???