HP LaserJet M104 Pro

Printing test pages helps determine whether the printer engine and the formatter are functioning. If the formatter is damaged, it might interfere with the engine test. If the engine-test page does not print, try removing power from the formatter and then performing the engine test again. If the engine test is then successful, the problem is almost certainly with the formatter

Engine test

NOTE:
The printer has an engine-test page in the firmware that is printed by opening and closing the tonercartridge door in a specific pattern. Use A4 or letter-size paper to print the engine-test page.

1. Make sure that paper is correctly loaded in the tray.
2. Turn the printer power on. Wait for the printer to reach the Ready state.
3. Open, and then close the toner-cartridge door four times at an interval of about two seconds to start the internal engine-test.
4. If the engine test is successful, an engine-test page prints. The test page should have a series of lines that are parallel to the short end of the page.

Drum rotation test check

The photosensitive drum, located in the imaging drum cartridge, must rotate for the print process to work. The printer drive gears rotate the photosensitive drum.

1. Open the toner-cartridge door.
2. Remove the toner cartridge and imaging drum cartridge.
3. Mark the drive gear on the imaging drum cartridge with a felt-tipped marker. Note the position of the mark.
4. Replace the toner cartridge and imaging drum cartridge and then close the toner-cartridge door. The startup sequence should rotate the drum enough to move the mark.
5. Open the toner-cartridge door and remove the toner cartridge and imaging drum cartridge. Inspect the gear on the imaging drum cartridge that was marked in step 3. Verify that the mark moved.
   
   If the mark did not move, inspect the drive gears to make sure they are meshing with the imaging drum cartridge gear. If the drive gears appear functional and the drum does not move, replace the imaging drum cartridge.