Lexmark Optra C710 Service Manual - Page 108

5016-001 Coupling Unit Service Check A 990 Service Engine Error. The coupling does not turn. B 990 Service Engine Error. The coupling motor turns. C 991 Service Engine Error. Indicates a problem with the coupling on and off sensors. Note: Verify correct operation of the mechanical parts of the coupling unit by manually resetting the coupling unit. Use the green coupling arm knob to reset the coupling unit and observe its operation. A 990 Service Engine Error - Motor does not turn on. FRU 1 Coupling Motor Cable MK2 Engine Board Action Disconnect the coupling motor at the inline connector and measure the resistance of the motor on the motor connector. It should measure between 9 and 15 ohms. If incorrect, replace the motor. The motor may be binding due to a problem in the motor mounting stay assembly. Remove the stay assembly and check for problems with the motor and coupling unit. Repair as necessary. If no problem is found and the motor does not turn, check cable MK2. • If incorrect, replace the cable. • If correct, replace the engine board. 2-42 Service Manual