To test the paper-out sensor used for everything except bottom-feed paper,
follow these steps:
1) Using standard procedures, remove the printer top cover.
2) Power on the printer without any paper inserted.
3) Configure a multimeter to measure between 0-5 volts DC.
4) Locate connector C9 on the logic board.
5) Connect the GND lead to pin 5 and the positive lead to pin 3. Without
any paper inserted in the printer, the measured voltage should be
approximately 4-5 volts.
6) Insert a piece of paper in the printer and monitor the multimeter. As
paper is inserted, the voltage should drop from 4-5 volts to almost
zero volts. Repeat this process several times to ensure proper
operation of the sensor.
If this change does not occur, the paper-out sensor is probably
defective and should be replaced.