Macbook Pro 2020 Touch Bar A2289 Ambient sensor and camera not working

[mon2]

Remove all power. Meter in diode mode. Red meter probe to ground, yes red. Black probe to point to test.

Check the scl pin of the i2c / smbus lines for devices that are faulty. Repeat for sda pin measurement. Post each value.

[nelusab]

Remove all power. Meter in diode mode. Red meter probe to ground, yes red. Black probe to point to test.

Check the scl pin of the i2c / smbus lines for devices that are faulty. Repeat for sda pin measurement. Post each value.

Forgive me for delay, it was my daughter's birth day.
Now the measurment results:

FT CAMERA
I2C_FTCAM_DSBL_SCL 0,591
I2C_FTCAM_DSBL_SDA 0,583

I2C_FTCAM_ISOL_SCL 0,550
I2C_FTCAM_ISOL_SDA. 0,557

I2C_FTCAM_SCL_R 0,439
I2C_FTCAM_SDA_R. 0,440

I2C_FTCAM_SCL 0,438
I2C_FTCAM_SDA. 0,439

ALS CAM
I2C_ALS_SCL_R 0,243 / MEASURED ON LVDS CONNECTOR
I2C_ALS_SDA_R. 0,242 / MEASURED ON LVDS CONNECTOR

I2C_ALS_SCL_R 0,440. / MEASURED ON R5315 / Flex cable LVDS removed from board
I2C_ALS_SDA_R. 0,441 / MEASURED ON R5316 / Flex cable LVDS removed from board

[mon2]

If you disconnect the ALS cable, what are the results? The diode values are different with and without this ALS cable connected to the logic board.

What is the history of this machine? Just stopped working? Liquid damage?

[nelusab]

I've checked again, the results measured on LVDS connector are not accurate , actualy they are the same with the results measured on board, for ALS CAM.

[nelusab]

Also measured I2C_ALS_SCL. 0,439
I2C_ALS_SDA. 0,439

[mon2]

These are good diode mode measurements for each. If practical, carefully measure the voltage to ground of these same lines. This is to confirm that the mandatory pull-up resistors are being pulled up to their logic '1' state when parked. Also note that the non-working camera / ALS / keyboard backlight will only be enabled when the LCD display lid is detected to be OPEN. This is my understanding. This open / close status is based on a hall effect sensor that operates between the trackpad and the display assembly. In the schematic will be a signal rail with the keyword 'LID' that will offer a '1' or '0' logic level based on the condition of the lid assembly. This signal should be reviewed. If the LID is considered to be closed, the above functions will disable.

[nelusab]

Hi mon2, I'm back with the measurements you requested

FT CAMERA
I2C_FTCAM_DSBL_SCL 0,591 - 1,800 V
I2C_FTCAM_DSBL_SDA 0,583 - 1,800 V

I2C_FTCAM_ISOL_SCL 0,550 - 1,816 V
I2C_FTCAM_ISOL_SDA. 0,557 - 1,816 V

I2C_FTCAM_SCL_R 0,439 - 1,816 V
I2C_FTCAM_SDA_R. 0,440 - 1,816 V

I2C_FTCAM_SCL 0,438. - 1,816 V
I2C_FTCAM_SDA. 0,439. - 1,816 V

ALS CAM
I2C_ALS_SCL_R 0,439. - 1,816 V
I2C_ALS_SDA_R. 0,439. - 1,816 V

Also measured :
PP3V3_G3S. - 3,33 V
SEP_CAM_DISABLE_DFF_L - 1,816 V
PP5V_G3S_ALSCAM. - 5,14 V

SMC_LID_LEFT. - 1,810 V
SMC_LID_RIGHT - 0 V ????????
IPD_LID_OPEN - 1,816 V

The measurements where made with the board out from inclosure.
It ssems there could be some issues with the right LID sensor, but could this affect ALS CAM?

[nelusab]

The board has only the left LID sensor, so the value for the right side is normal

[nelusab]

What does mean DFF from SEP_CAM_DISABLE_DFF_L ?
If it means DEFAULT it sould be in Low state?

[mon2]

See attached. This signal is used by the multiplexer @ U8502.

If this signal is LOW then this state is considered to be true (denoted with the _L suffix in the netname label). That is, this is an 'active LOW' enable. When LOW (0 volts) then the camera is DISABLED and vice-versa.

What is the voltage to ground of this signal ?

[nelusab]

In a privious post is mentioned
SEP_CAM_DISABLE_DFF_L - 1,816 V

[mon2]

Appears to be dustgate:

https://www.forbes.com/sites/jaymcgr...-displays/amp/

[nelusab]

The scrren works well, without any lines or glitches. I've dissasembled from the topcase and checked the flex cables on microscope. No noticeable damage, and as I said works well, I mean the graphic function.
The laptop had macos Catalina installed on it and all functions, including ALS cam, FT cam, KB backlight, where working. During an system upgrade something happened resulting in a kernel panic, so the upgrade process couldn't be finished, the laptop entered in a loop booting mode, the progrss bar riching half on its way and restarting.
So I performed a DFU revival, followed by a DFU restoration without succes. The DFU restora prcess works ok, but on the OS install process the same issue appeared.
I had to install SONOMA on an external SSD, booting from it and cloning the system on the internal SSD. Now the laptop is booting into SONOMA, everyting works properly, unless the functions I mentioned.
So an upgrade process caused the problem not the dust, Any ideeas?

[mon2]

Too many different posters in this same thread.

After the DFU - does your touchbar function? Can you boot Catalina with an external media for testing?

[nelusab]

The touch bar fuction works ok, I couldn' check it until installing the OS, but now works ok. Also the screen backlight is working, the system boots prety well.

[nelusab]

I've allready booted from Catalina. Catalina was the first OS i've cloned, then i.ve tried an upgrade with the results I've reported, and after that I've cloned SONOMA on internal SSD. So yes I can boot on Catalina from an external SSD, having both SONOMA and CATALINA on external SSD. As I said the behaviour is the same on both OS

[mon2]

Is the camera hardware detected under Sonoma?

Review this thread:

Camera stopped working after updating mac… - Apple Community

[nelusab]

No, harware not detected, I also checked the harware with Apple Diagnostc tool and no issues where listed. I'm asking myself if something happened with ROM SPI during the first upgrade from Catalina to Sonoma. The upgrading process includes an iBoot version upgrade, and perhaps some changes in the U4770 ROM bin file.

[mon2]

From post # 23 - what is the history of this machine?

You have only upgraded the software and lost these functions?

If yes, then it is just crap software from Apple. Suggest to contact their technical support wannabe propeller heads to ask how they broke this machine. Checking hardware is a waste of time since the software they have supplied broke a working logic board from one OS to another. The enumeration of the camera will be over I2C / SMBUS. Such a bus requires a bus master which is driven by firmware. Either way, they wrote the software so they should know how to fix it. Do investigate with their technical support and continue to post your updates here with their feedback and ideally the resolution.

Pos # 37 links a work around by rolling back the OS version which you may want to consider.

[nelusab]

Solved! It was the display flex cable. The 5V CAM line was damaged.