Page: 80Service Guide OL400Chapter 4 Failure & Repair AnalysisRAP 05:Engine Error - Fusing Problem AlarmSTARTTurn the power OFF, then ON. Does a fuser unit alarm occur immediately?NO Go to AYES Is the thermistor open (the normal resistance should be about 100k ohmsat room temperature)? Measure between pins 1 and 2 of the cable connected toengine controller circuit board J2.YES Replace the fuser assembly.NO Is the thermistor shorted? (See above)YES Replace the fuser assembly.NO Replace the engine controller circuit board.ENDAPower OFF, then ON.Does the fuser lamp glow? (Check this from the rear vents of the printer.)YES Is the thermistor open? (See above)NO Replace the engine controller circuit board.YES Replace the fuser assembly.NO Is the fuser lamp open? (With the upper cover open, lift the upper unitand measure the resistance between the heater AC connections.) (0ohms is normal. Infinite resistance is open.) Check for propercontact between the fuser's AC contacts and the power supply.YES Replace the fuser assembly.NO Is the HEAT signal turned on? (HEAT signal at engine controllercircuit board IC3 pin 75.)NO Replace the engine controller circuit board.YES Replace the power supply unit.
