While troubleshooting a C2220 code (1st transfer not turning) the toner door sensor has stopped responding properly.
The message to close the Toner Supply unit remains after closing it & turning the screw in.

PRCB CN125B Pins 1 2 & 3 (Top Left of connector) should be Ground, signal out & Vcc of 5V for the sensor per the wiring diagram.
With the sensor unplugged i am getting 0 / 5 / 0
Plugged in I get 0 / 2.3 /1.2

Occasionally if I unplug the sensor & plug it back in the message will clear (ie tell me now to close the front doors) but this is random.

The connector on the PRCB to the Right has 2 Vcc points that give a good 5V reading (as do the power connectors on the right side of the board)
The PRCB was swapped & gives the same readings.

If anyone can confirm those voltages it would be appreciated

(I am currently trying to source another Photosensor)

FYI the C2220 code - M9 / PRCB / DCPS/4 all swapped; wire harness inspected as best possible
RL3 is not turning on - do not know why
Firmware has been kept up to date
The First Transfer Belt does not appear to be faulty / short screws are being used where necessary / worn ball bearing recently changed

Any help appreciated