Brother HL-4040CN Service Manual page 33

Error code 38
Print Unable 38
Turn the power off and then back on again.
THM sensor failure
Error code 39
Print Unable 39
Turn the power off and then back on again.
HUM sensor failure
Step
1 Harness connection failure of
THM/HUM sensor
2 THM/HUM sensor failure
3 Engine PCB failure
Error code 3A
Print Unable 3A
Turn the power off and then back on again.
Error code 7C
Print Unable 7C
Turn the power off and then back on again.
Engine communication error
Step
1 Harness connection failure
between engine PCB and
main PCB
2 Engine PCB failure
3 Main PCB failure
Error code 3D
Print Unable 3D
Turn the power off and then back on again.
Main PCB failure (Any of the PCBs is judged to be failure by the PCB checker, or it is not tested
with the checker.)
Step
1 Main PCB failure
2 Engine PCB failure
Cause
Check the harness connection of the THM/HUM
sensor and reconnect it.
Replace the THM/HUM sensor holder ASSY.
Replace the engine PCB ASSY.
Cause
Check the harness connection between the engine
PCB and main PCB, and reconnect it.
Replace the engine PCB ASSY.
Replace the main PCB ASSY.
Cause
Replace the main PCB ASSY.
Replace the engine PCB ASSY.
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Remedy
Remedy
Remedy
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