C2557 (bizhub C754/C654)
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Contents
| Trouble type | Abnormally low toner density detected black TCR sensor | 
| Trouble code | C2557 | 
| Rank | B | 
| Detection timing | When sampling data is determined in TC ratio calculation control, TCR sensor output is higher than a predetermined value for a predetermined number of times in a row even though there is toner in the sub hopper. | 
| Trouble isolation | – | 
| Relevant electrical parts | -Developing unit /K -Toner cartridge /K -Toner empty sensor/K (PZS/K) -Toner supply motor/K (M12) -Toner cartridge motor /CK (M14) -Printer control board (PRCB)  | 
(2)Procedure
| Step | Action | Control signal | Location of electrical components | 
| 1 | Perform image troubleshooting procedure if image density is low. | – | – | 
| 2 | Check the connector between M12-relay CN258-PRCB CN3 for proper connection, and correct as necessary. | – | – | 
| 3 | Check the connector between M14-relay CN321-relay CN428-PRCB CN4 for proper connection, and correct as necessary. | – | – | 
| 4 | Check the connector of M12 and M14 for proper drive coupling and correct as necessary. | – | – | 
| 5 | M12 operation check(At this time, IU must be non-installation.) | PRCB CN3-13 to 16 | 24-C | 
| 6 | M14 operation check | PRCB CN4-5 to 8 | 3-K | 
| 7 | Replace M12 (Part# A00JM12100) and M14 (Part# 9314130021) | – | – | 
| 8 | Reinstall developing unit /K | – | – | 
| 9 | Reinstall toner cartridge | – | – | 
| 10 | If the toner empty sensor and its surroundings inside the sub hopper are dirtied with toner, clean them. | – | – | 
| 11 | Replace the developing unit /K (Part# A2X203D) | – | – | 
| 12 | PRCB ICP23 or ICP24 conduction check | – | – | 
| 13 | Replace PRCB. (Part# A2X0H00102) | – | – | 
- Link to the wiring diagram (N.1. bizhub C754/C654)
 - Link to the layout drawings for related parts by each trouble code (S.64. C2557)
 
K.3.7.16 (Link to the Field Service Manual)
