3-8 Phaser 4400 Laser Printer Service ManualToner Sensor FailureLow Toner is not displayed when the Print Cartridge appears to be empty.Low Toner Sensor Failure Troubleshooting ProcedureStep Actions and Questions Yes No1 Print a Test Print. Inspect the print quality.Is the print light?Go to step 2. Return toServiceFlowchart onpage 2-2.2 1. Replace the Print Cartridge (PL 8.1 on page 7-20).2. Run 5 test prints (Configuration Page or Demo Page)and inspect the print quality following the guidelinesin Image-Quality Checkout Procedures onpage 3-41.Does the print quality appear acceptable?Go to step 3. Go to Light(Undertoned)Prints onpage 3-54.3 1. Enter Service Diagnostics and select Sensor Tests.2. Scroll to Toner Sensor and press OK.3. Open the Front Cover and cheat the Front CoverInterlock.4. Remove and replace the Print Cartridge two or threetimes.Does the message on the Front Panel displayalternate between Toner Normal and Toner Lowas you remove and replace the Print Cartridge?Replace theEngine LogicBoard (RRP9.3 onpage 6-89).Go to step 4.4 1. Switch the printer power OFF.2. Remove the Front Cover (RRP 1.6 on page 6-11) andthe Left Front Cover (RRP 1.7 on page 6-12).3. Cheat the Front Cover Interlock.4. Switch the printer power ON.5. On the connector PWB, check the voltage betweenP/J42 pin 4 and frame ground.Is the voltage 0.0 VDC with the print cartridgeinstalled, and +3.3 VDC with the print cartridgeremoved?Go to step 7. Go to step 5.5 Check the voltage between P/J42 pin 3 and pin 1.Is the voltage +24 VDC?Replace theToner Sensor(RRP 5.2 onpage 6-59).Go to step 6.6 On the Connector PWB, check the voltage betweenP/J231 pin 11 and pin 12.Is the voltage +24 VDC?Replace theConnectorPWB (RRP9.7 onpage 6-94).Go to step 8.7 On the connector PWB, check the voltage betweenP/J231 pin 9 and frame ground.Is the voltage 0.0 VDC with the print cartridgeinstalled, and +3.3 VDC with the print cartridgeremoved.Go to step 8. Replace theConnectorPWB (RRP9.7 onpage 6-94).
