Brother HL-4000CN Service Manual page 238

Black Toner Cartridge Detached FIP
Step
Initial setting
Check the following for evidence of fault.
Cartridge replacing condition
Toner cartridge switch ASSY (K) replacing
1 condition
Toner cartridge switch ASSY (K) actuator
replacing condition
Toner cartridge switch ASSY (K)
connector replacing condition
Checking toner cartridge switch ASSY
Does toner cartridge switch ASSY
2 function normally?
Using diagnostic tool, check by digital
input test.
Checking drive PWB for signal
3
Is P/J51-31PIN<=>P/J51-32PIN 0VDC?
Checking toner cartridge switch ASSY (K)
4 for signal
Is P/J434-2PIN<=>P/J434-1PIN 0VDC?
Checking toner cartridge switch ASSY (K)
for continuity
5 Is P434-2PIN<=>P434-1PIN of toner
cartridge switch ASSY (K) continuous
normally?
Checking harness ASSY TNR for
6 continuity
Is J51<=>J434 continuous normally?
Checking drive PWB for signal
7
Is P/J42-3PIN<=>P/J42-14PIN 0VDC?
Checking MCU and HVPS PWB for signal
8 Is P/J12-28PIN<=>P/12-17PIN of MCU
and HVPS PWB 0VDC?
Checking harness ASSY DRV2 for
9 continuity
Is J12<=>J42 continuous normally?
Check
V-28
Remedy
Yes
Replace the parts
Go to step [2]
concerned
Replace MCU and
Go to step [3]
HVPS PWB
Go to step [4]
Go to step [7]
Go to step [6] Go to step [5]
Replace toner
cartridge
Go to step [6]
switch
ASSY (K)
Replace
Go to step [7] harness ASSY
TNR
Replace drive
Go to step [8]
PWB
Replace MCU and
Go to step [9]
HVPS PWB
Replace
Replace MCU and
harness ASSY
HVPS PWB
DRV2
No