Dell P1500 Personal Mono Laser Printer - Manual (Page 56)

The printer is busy receiving or processing data, or printing a test page. In
addition, the toner in the toner cartridge is getting low.
What you can do:
Remove the toner cartridge and gently shake it to extend the life of
the cartridge.
Replace the toner cartridge .
Press and release Cancel to cancel the print job.
Press and hold Cancel to reset the printer.
What this light sequence means:
The printer is waiting until a print timeout occurs, or until it receives
additional data.
What you can do:
Press and release Cancel to cancel the print job.
Press and release Continue to print the contents of the print buffer.
Press and hold Cancel to reset the printer.
What this light sequence means:
The printer is waiting until a print timeout occurs, or until it receives
additional data. In addition, the toner in the toner cartridge is getting low.