iMac (27-inch, Mid 2010) — General Troubleshooting 25
2010-09-09
Diagnostics
The following diagnostics are required for this product:
• Apple Service Diagnostic (ASD), version 3S140
• For iMac (27-inch, Mid 2010): Apple Hardware Test (AHT), version 3A202
• Bluetooth Service Diagnostic (BSD) 1.1
Sensors Errors
Run latest available service utilities to determine if any thermal sensors or blowers are malfunctioning. When a
test reports an error, reseat appropriate connections and check that all air ows are free from obstruction. If issue
persists, replace the corresponding part (sensor, blower, logic board, video card, or power supply). See chart below
for correlation between aected sensor, sensor location, and additional checks to perform.
Note: AHT can be run by pressing the D key on startup (if hard drive was not reformatted, or if adequate system
specic restore DVD is inserted). If a sensor error is detected, AHT will report an error code containing the aected
sensor name (ex: “4SNS/1/40000000 TC0H” error code reports to sensor TC0H).
Sensor Suspected part and Location Suggested Action Notes
TA0P Excessive incoming Ambient air
temperature, or Ambient temp
sensor damaged/disconnected
from logic board.
Verify that incoming/outgoing air vents
are free from obstruction , that sensor
cable is securely connected to the top
edge of the logic board and attached to
the left speaker housing. Replace sensor
cable if damaged.
All fans ramp at full
speed if sensor is
disconnected.
T00p Excessive Optical Drive area
temperature, or ODD temp
sensor damaged/ disconnected
from logic board.
Verify sensor cable is securely connected
to the logic board and the sensor
is properly attached to the ODD
mechanism. Replace sensor cable if
damaged.
The ODD fan will run
at full speed if sensor is
disconnected.
TH00 Excessive Hard Drive area
temperature, or HDD temp
sensor damaged/disconnected
from logic board. Use the
correct sensor cable, each drive
vendor has a unique sensor
cable model.
Verify sensor cable is securely connected
to top left side of logic board and it’s
connected to hard drive. Check for
damaged cable on logic board.
The HD fan may run at
full speed if the sensor
is disconnected.
Tm0p Excessive logic board
temperature (this sensor is part
of logic board)
Test with known-good logic board
TL0p Excessive LCD panel area
temperature, or LCD temp
sensor damaged/disconnected
from top of logic board
Verify that the LCD sensor cable is
securely connected to the logic board
and the sensor is attached to the LCD.
Replace the sensor cable if damaged
The CPU fan will run at
full speed if the sensor
is disconnected.