Dell P1500 Personal Mono Laser Printer - Manual (Page 57)

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.
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 Continue to print the contents of the print buffer.
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 flushing corrupted print data.
The printer is processing data or printing pages, but the resolution of a
page in the current print job is reduced from 600 dots per inch (dpi) to
300 dpi in order to prevent a memory full error.
What you can do:
Wait until the operator panel returns to Ready/Data to print other jobs.
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 flushing corrupted print data. In addition, the toner in the
toner cartridge is getting low.