Brother HL-2140 printing black pages.

Here is the procedure for resetting the Toner flashing light on Brother HL-2140 (sources for other answers here and self testing - specific to HL-2140)

• Open the front cover and leave open.
• Turn the printer off.
• Hold the "white button" while turning the printer on. (All panel lights should be on.)
• Release the "white button".
• Press the "white button" 2 times (Pause, wait for all lights to come on.)
• Press the "white button" 5 times. (All lights to come on again, then go out.)
• Cancel "maintenance driver" install, if prompted
• Close cover.
• Power cycle printer.

This will:

• reset the toner light (stop blinking)
• restore the printing darkness (when toner light flashes, printer prints lighter to save toner)
• keeps the printed page counts and drum life info

In the Brother HL-2140 printer, it shows the Toner led light is on. Even if there is plenty of toner on the cartridge. It just wont print anything after initiating a print job since the toner light is on.Here is a trick on what you need to do:

1. Turn off the Brother HL-2140 printer.
2. Open the front access door to take out the toner from the carriage.
3. Notice that on both sides of the toner, you will see a small hole which is most probably the sensor.
4. What you do is to cover the sensor holes with masking tape and color the tape with black marker. Or, you can also use an electrical tape to cover them.
5. Shake the toner so that the ink inside will redistribute evenly.
6. Return the toner to the carriage and try to initiate a print again.

That's it!