GE Giraffe Service Manual page 89

Alarm Message Meaning
The sensor
plug thermistor
Oxygen System temperature
Failure 1 reading is out
of the range:
15C-55C.
The RH reading is
out of valid range:
Oxygen System
1-99. When out of
Failure 2
range it displays 0
in service mode.
The checksum test
Oxygen System performed during
Failure 3 power up testing
failed.
Analog to digital
converter circuit
self test failed. The
Oxygen System
reading of Vtest
Failure 4
is out of the valid
range: 1.216V-
1.254V.
After calibration,
both supply
valves are
Check O2 opened and after
supply approximately 20
seconds, sensor1
reading is not
greater than 23%.
© 2001 by Datex-Ohmeda, Inc.. All rights reserved.
Cause
Unit is cold: <15
degrees C.
Cooling fan is not
running when the
sensor housing
temperature gets
above 50 degrees.
Defective sensor plug
thermistor or cable.
Defective servo O2
board.
Defective sensor plug.
Defective servo O2
board.
Defective
Microcontroller.
Defective Servo O2
board.
O2 supply is not
connected.
Chapter 4: Troubleshooting
Action
Allow unit to warm up.
Test the cooling fan. Refer to the Tips section
4.7.3.3.
Disconnect the cable and measure the
resistance of the thermistor between J85.4
and J85.5. Refer to R/T chart in the Tips
section 4.7.3.4. If sensor is shorted, open, or
values don't agree with the R/T chart, replace
the sensor plug assembly or the cable.
If resistance is in range replace the servo O2
board.
Measure the humidity sensor voltage
between J85.2 and J85.1. If the voltage is
outside the range of 0.7V- 4.0V, replace the
sensor plug assembly.
If it is in the correct range, replace the servo
O2 Board.
Replace microcontroller U6 on the Servo O2
board.
Replace servo O2 board.
Verify O2 supply, minimum 45psi (310kPa) is
connected to the inlet.
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