User Guide

iMac (27-inch, Late 2009) Symptom Charts — Startup and Power 31
2009-12-16
Press power button while 3.
monitoring diagnostic LEDs.
Verify if LED #2 turns ON and
remain ON after pressing
the power button. You may
alternately check for a power
request signal between pin 12
and pin 1 of logic board.
Yes Power supply functioning and
logic board detects supply
voltages. Go to Won’t Start
Up symptom ow.
No Go to step 4.
Disconnect AC cable then 4.
remove power supply and
carefully inspect connectors
between AC inlet and power
supply, then DC connectors and
cables between power supply
and logic board, for damage or
poor connections.
Yes Replace damaged part. P16
No Go to step 5.
Inspect power button and 5.
verify if it is properly connected
to the logic board.
Yes Go to step 6.
No Reconnect power button.
Disconnect power button from 6.
logic board. Inspect cable and
connector for damage. Verify
continuity between the two
pins of power button when it is
pressed.
Yes Power button is functioning
correctly. Reconnect power
button to logic board and
go to step 7.
No Power button faulty. Replace
rear housing (which includes
power button).
X14
Press power button and Verify 7.
if system turns ON. You may
alternately check for presence
of a 12V DC signal between
pin 11 and pin 1 of logic board
when power button is pressed.
Yes Power supply functioning. If
system still won’t boot, go
to Won’t Start Up symptom
ow.
No Replace DC power cable.
Go to step 8.
X03
Press power button and verify if 8.
system turns ON.
Yes Issue solved with replaced DC
power cable.
No Replace power supply.
Go to step 9.
P01
Press power button and verify if 9.
system turns ON.
Yes Issue solved with replaced
power supply.
No Reinstall power supply and
replace logic board.
M01
Note: If No Power symptom persists after all steps have been followed use minimum
conguration troubleshooting to proceed. Try disconnecting hard drive, optical drive, AirPort,
Bluetooth, and SD card modules to determine if one of them is preventing the power supply
from functioning.