Brother HL-3450CN Service Manual page 303

CHAPTER 8 TROUBLESHOOTING
Error Code
Heater Fan (HTFAN)
Concerned Part
Confirm the connection of a heater fan connector.
Is DCN14 of IOD1 properly connected with a connector of the heater fan ?
Is DCN1 of IOD1 properly connected with 11CN of MCTL PWB ?
Check the voltage (HTFANON-P).
Is the voltage between DCN14-10 and 11 to be a rising edge ?
Is the voltage between DCN1-35 and 44 to be a rising edge ?
Is F4 error cleared ?
Job is complete.
F4
NO
NO
YES
NO
YES
NO
NO
YES
Connect them properly.
Is F4 error cleared ?
NO
Replace the heater fan.
Replace the IOD1 PWB.
Replace the MCTL PWB.
IOD1
MCTL
DCN1 DCN14
11CN
5
PGND
44
44
HTFANON-P
35
35
DCN1
+24V-1
17
PGND
25
8-40
YES
Job is complete.
12
Heater Fan
HTFANON-P
10
PGND
HTFAN
11
HTFANERR
12