1998 ISUZU TROOPER sensor

1BÐ92 AIR CONDITIONING
TROUBLESHOOTING
Troubleshooting, Its Overview and Procedures
The full automatic heater and air conditioner equips with the "Self-Diagnosis Function" to check its major
components.
This function makes access to the sensors, actuators and blower fan motor system easier when checking
them up and, when a failed part is located, this function restores its original performance.
When implementing the troubleshooting, this self-diagnosis function narrows the range to be searched at
the first step, then check relevant parts one by one according to the "Checking Procedures by Failed
Location" As for a location this function is unappreciable, the system accurately determines characteristics
of a given trouble and checks relevant parts according to the "Checking Procedures by Failed Location".
The following illustrates basic troubleshooting flow.
1. Basic Troubleshooting Flow
Occurrence of a trouble
Refer to the check list for
the inspection.Locate the failed location.
Check the failed part.
Correction
Correction
Correction
Troubleshooting by the
self-diagnosis function.Reference the "Check
Procedure by Failed
Location" for the inspection.
Reference the "Check
Procedure by Failed
Location" for the inspection.Correction
Check the cooling / heating
cycles.
End OK OK OK OKNG
NG
NG
NG
NG OK
Check if the automatic
heater / air conditioner
control unit indicator LED
is turned on.Check the power supply and
circuit on the automatic
heater / air conditioner control
unit.
Troubleshooting not relying
on the self-diagnosis
function(troubleshooting
by failure type).
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AIR CONDITIONING 1BÐ97
TROUBLESHOOTING WITH SELF-DIAGNOSIS FUNCTION
1. Overview of Self-Diagnosis Function
The self-diagnosis is implemented in 3 steps for each target. For detail of check procedure contained in
each step, refer to the relevant section of "Check Procedure by Failed Location" listed in the Self-
Diagnosis Operation Procedure.
For turning on the self-diagnosis function and switching of the check step, refer to the flow chart given
below. You can reset the self-diagnosis function by turning the ignition switch off or turning the DEF
switch on for 3 seconds.
2. Self-Diagnosis Operation Procedure
While holding both the Auto switch and the DEF switch on the
automatic heater/air conditioner panel, turn the IG off and then
on.

Does the A/C LED flash every 0.5 second interval?
Press the A/C switch once.
(The past trouble
diagnosing function will
be turned on.)

Does the A/C LED flashes every 0.5 seconds?

Does each output equipment functions normally according to
operation of the temperature setting lever?
Press the DEF switch for 3
seconds consecutively or turn on
and off the IG.
Failure on the
output equipment
or the harness.
Preparations
(1) Set the IG to the OFF mode.
(2) Apply 60W bulb light to the sun sensor.
(3) Set the temperature setting lever on the automatic heater/air
conditioner panel to the center position (25C).
(4) Set the fan switch on the same panel to the Auto position.
End of the self-diagnosis.(The current trouble diagnosing function will be turned on
approximately in 10 seconds.)
YESNO
YESNO
NO
YES
Refer to *1.
Refer to *2.

1BÐ98 AIR CONDITIONING
*1. Displaying the Current Trouble Diagnosing Table
Start the engine while holding down both the Auto switch and the DEF switch on the control panel, and
the table will appear in approximately 10 seconds to the indicator lamp (LED) of the air conditioning
switch. Result of the diagnosis along the following 9 items will be shown one by one in 0.5 second
interval irrespective of presence or absence of a trouble for a given item. When the display 9 items is
completed, it is repeated with 3 seconds of interval in between. A failed item is indicated by flashing of
the LED that is repeated 3 times within 0.5 seconds. If a trouble is indicated, you can locate the failed
section by knowing when in the total sequence it has been displayed.
Items for Current Trouble Diagnosis
As shown above, display of result along nine items is repeated with 3-second interval in between.
Note 1: When checking the solar radiation sensor, apply sufficient light using a 60W bulb.
Otherwise, it can be diagnosed as failed.
Note 2: If the temperature setting lever is set on both ends (one set to 18¡C, blue scale = Full cool and
the other to 31¡C, red scale = Full hot), they can be diagnosed as failed.
Note 3: Likewise, the fan switch can be diagnosed as failed if set on both ends.
LED on
LED off Indication for presence
of a troubleIndication for normal state
0.5 0.5 0.5
3 seconds interval
ON
OFF
Display pattern Failed part
Normal pattern
In car sensor
Ambient sensor
Sun sensor (Note 1)
Duct sensor
Temperature control lever (Note 2)
Fan switch (Note 3)
Mix actuator
Mode (blow port) control
Intake (fresh air/interior air switching) control
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AIR CONDITIONING 1BÐ99
*2. Displaying the Past Trouble Diagnosing Table
The past trouble diagnosis displays only the items on which trouble has recurred 16 times in the past.
If you press the air conditioning switch once while the current trouble diagnosis is taking place, display
of the past trouble diagnosis will appear on the indicator lamp (LED) of the air conditioning switch.
Results of the diagnosis along the following five items are displayed one by one in 0.5 second interval
irrespective of presence or absence of a trouble. A failed item is indicated by flashing of the LED that is
repeated 3 times within 0.5 seconds. You can locate the failed section by counting in what sequence it
has been displayed.
Items for Past Trouble Diagnosis
LED on
LED off Indication for presence of a trouble Indication for normal state
0.5 0.5 0.5
3 second interval
Display pattern
ON
OFFNormal pattern
In car sensor
Ambient sensor
Sun sensor
Duct sensor
Mix actuatorFailed part
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*3. Check of Output Equipment
FAN
MIX
MODE
DOOR
INTAKE
DOOR
SET UP
TEMPERATURE
100
(%)
33.5
F/H
VENT
B/L
FOOT
D/F
DEF
REC
MIX
FRE
F/C 20 21 22 23 24 25 26 27 28 29 30 F/H (%)
F/C
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1BÐ100 AIR CONDITIONING
Independent check of sensors
Replace the control unit.
Sensors Allowable range Check method
In car sensor
Ambient sensor
Sun sensorRefer to the sensor resistance curve.
Refer to the sensor resistance curve.
100 ohms maximum in forward and 0.02 mA
minimum when exposed to 60W incandescent lamp.Chart 1
Chart 2
Chart 3
Replace the harness and
connector.
Replace the sensors.
Check the related harness and
connector
Normal ?
Normal ?NONO YES
YES
INSPECTION BY FAILED LOCATION
Inspection of the Sensors
When the self-diagnosis function has determined that trouble is present on the sensors, check them
according to the following flow chart.
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AIR CONDITIONING 1BÐ101
Chart 1: In Car Sensor
NOReplace the sensor.
NODisconnection of the harness.
Failure on the automatic heater/air
conditioner control unit.
YES
Disconnect the in car sensor connector (I-34).
YES
Is the sensor performance normal? (refer to
the later section on "Check Up")
Are conduction provided between the
following connector terminals on chassis
harness side?:
No.3 and No.1 .
No.4 and No.11 .
I-33I-34
I-33I-34
I-33I-34
1
112
123
134
145
156
167
178
189
1910
20
0.3 BR/B
0.5 B/L
111
In car Sensor Auto A/C Control Unit
(In car Sensor)
(Sensor GND)4 3
I-33I-34
12 43
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1BÐ102 AIR CONDITIONING
Chart 2: Ambient Sensor
NOReplace the ambient sensor.
NOFailure on the harness.
Connect the ambient sensor connector.
Replace the automatic heater/air conditioner
control unit.
YES
Disconnect the Ambient sensor connector
(C-86).
YES
Is performance of the ambient sensor
normal? (Refer to the later section on
"Check Up".)
Is resistance between the following
connectors normal?
No.2 and No.11 .
I-33I-33
I-33C-86
H-24
1
112
123
134
145
156
167
178
189
1910
20
0.3 LG/B
0.3 B/L
112
Ambient Sensor Auto A/C Control Unit
(Ambient Sensor)
(Sensor GND)I-330.3 LG/B
0.3 B/LH-24 8
H-24 9
C-86 1
C-86 2
17 18 16 15 1478 6 5
12 13 11 10 94 132
5 6 7 8
15 16 17 18 142 3 41
10 11 12 13 9
12
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AIR CONDITIONING 1BÐ103
Chart 3: Sun Sensor
NOReplace the sun sensor.
NOReplace the harness.
Replace the automatic heater/air conditioner
control unit.
YES
Disconnect the sun sensor connector (I-35).
YES
Is performance of the sun sensor normal?
(Refer to the later section on "Check Up".)
Is the conduction provided between the
following chassis harness side connector
terminals?
No.3 and No.1 .
No.11 and No.2 .
I-35I-33
I-35I-33
0.3 LG/W
0.3 B/L
113
Sun Sensor Auto A/C Control Unit
(Sun Sensor)
(Sensor GND)I-33I-351
I-352
I-33I-35
211
112
123
134
145
156
167
178
189
1910
20
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