2007 ISUZU KB P190 display

9A1-4 RESTRAINT CONTROL SYSTEM

Basic Knowledge Required
Before using this section of the Service Manual, some
basic knowledge is required. W ithout this knowledge,
you will have trouble using the diagnostic procedures in
this section. Use care to prevent any harm or unwanted
deployment. Read all cautions in the service manual
and on warning labels attached to SRS components.

Basic Electrical Circuits
You should understand the basic theory of electricity
including series and parallel circuits, and understand
the voltage drops across series resistors. You should
know the meaning of voltage (volts), current (amps),
and resistance (ohms). You should understand what
happens in a circuit with an open or a shorted wire. You
should be able to read and understand a wiring
diagram.

“Flash Code” Diagnostics
Flash code diagnostics can be used to read active
codes and to determine if history codes are present but
cannot be used to clear codes or read history codes.
Flash code diagnostics is enabled by grounding
terminal 4, shorting to terminal 13 of the DLC, with the
ignition switched “ON”. Grounding terminal 4 of the DLC
pulls the “Diagnostics Request” input (Terminal 1) of the
SRS control unit low and signals the SRS control unit to
enter the flash code diagnostic display mode.
060R300052

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ISUZU KB P190 2007

RESTRAINT CONTROL SYSTEM 9A1-5

The SRS control unit displays the trouble codes b
y
flashing the warning lamp. Each code that is displayed
will consist of a number of flashes which represents the
tens digit, a 1.2 second pause, followed by a number o
f
flashes which represent the ones digit of the code. Each
code is displayed once before moving on to the next
code. After all the codes have been displayed, the
entire code sequence will be continually repeated until
ground is removed from terminal 4 of the DLC.

Two special codes exist when reading in the flash code
mode (Flash Code 12 and Flash Code 13). “Flash
Code 12” will always be the first code displayed when
the flash code mode is enabled. Code 12 is not an
indication of an SRS problem but an indication that the
flash code mode has been enabled. If there are no
active or history codes present, the SRS control unit will
display code 12 until ground is removed from the DLC
at terminal 4. “Flash Code 13” will be displayed i
f
history codes are present. To read the history codes, a
scan tool must be used.







RTW 79AMF000101
DATA LIST (Tech 2)

DISPLAY on Tech 2 UNIT VALUE
Battery Voltage
V 12.0
Driver Airbag Squib Circuit Resistance Ohm 1.70-4.33
Passenger Airbag Squib Circuit Resistance Ohm 1.31-3.08
Driver Seatbelt Status Buckled/
Not Buckled Buckled/
Not Buckled


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ISUZU KB P190 2007

9A1-6 RESTRAINT CONTROL SYSTEM

Diagnostic Trouble Codes
Choose and trace an appropriate flowchart by the numbers listed below to find fault and repair.
DTC Flash Code Description
– 12 Diagnostic Display Mode (Flash Code only)
– 13 Diagnostic Display Mode (Flash Code only)
B0015 15 Passenger Air Bag Squib Circuit High Resistance
B0016 16 Passenger Air Bag Squib Circuit Low Resistance
B0018 18 Passenger Air Bag Squib Circuit Short to GND
B0019 19 Passenger Air Bag Squib Circuit Short to Battery Voltage
B0021 21 Driver Air Bag Squib Circuit High Resistance
B0022 22 Driver Air Bag Squib Circuit Low Resistance
B0025 25 Driver Air Bag Squib Circuit Short to GND
B0026 26 Driver Air Bag Squib Circuit Short to Battery Voltage
B0029 29 Passenger Pretensioner Squib Circuit High Resistance
B0031 31 Passenger Pretensioner Squib Circuit Low Resistance
B0033 33 Passenger Pretensioner Squib Circuit Short to GND
B0034 34 Passenger Pretensioner Squib Circuit Short to Battery Voltage
B0041 41 Driver Pretensioner Squib Circuit High Resistance
B0042 42 Driver Pretensioner Squib Circuit Low Resistance
B0045 45 Driver Pretensioner Squib Circuit Short to GND
B0046 46 Driver Pretensioner Squib Circuit Short to Battery Voltage
B0051 51 Air Bag Squib Circuit Activated (Clash)
B0052 52 Pretensioner Squib Circuit Activated
B0055 55 Vehicle Variant Missing
B0061 61 Warning Lamp Circuit Failure
B0062 62 Battery Voltage Too High
B0063 63 Battery Voltage Too Low
B0071 71 SRS Control Unit Internal Fault


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ISUZU KB P190 2007

9A1-8 RESTRAINT CONTROL SYSTEM

Circuit Description
W hen the ignition switch is first turned “ON”, “Ignition 1”
voltage is applied from the “SRS” fuse to the SRS
control unit at the “Ignition 1” input terminals “1”. The
SRS control unit responds by flashing the “SRS”
warning lamp seven times, while performing tests on
the SRS.

Notes On System Check Chart
1. The “SRS” warning lamp should flash seven times after the ignition is first turned “ON”.
2.
After the “SRS” warning lamp flashes seven times, it
should turn to “LOCK”
3. This test checks for the proper operation of the “Serial Data” line. This test will also determine
whether history diagnostic trouble codes are stored
and, if so, identify them.
4. Improper operation of the “SRS” warning lamp is indicated. This test differentiates between ‘a
warning lamp stays “ON” condition’ and ‘a warning
lamp does not come “ON” condition’.
5. This test checks for proper operation of the “Serial Data” line. This test will also identify the stored
diagnostic trouble codes and whether they are
current or history.
Diagnostic Aids
The order in which diagnostic trouble codes are
diagnosed is very important. Failure to diagnose the
diagnostic trouble codes in the order specified ma
y
result in extended diagnostic time, incorrect diagnosis
and incorrect parts replacement.


SRS Diagnostic System Check

Step Action Yes No
1 Note the “SRS” warning lamp as the ignition switch is turned
“ON”.
Does the “SRS” warning lamp flash seven (7) times? Go to Step 2 Go to Step 3
2 Note the “SRS” warning lamp after it flashed 7 times.
Does the “SRS” warning lamp go “OFF”? Go to Step 4 Go to Step 5
3 Note the “SRS” warning lamp as the ignition switch is turned
“ON”.
Does the “SRS” warning lamp come “ON” steady? Go to Chart B. Go to Chart C.
4
1. Note the “SRS” warning lamp as the ignition switch is turned
“ON”.
Ignition switch is at “LOCK”.
2. Connect a scan tool to data link connector.
3. Follow direction given in the scan tool instruction manual.
Ignition switch is “ON”.
4. Request the SRS diagnostic trouble code display, recode all
history diagnostic trouble code(s), specifying as current or
history in repair order.
Is (are) diagnostic trouble code(s) displayed?
Ignition switch
“LOCK”.
W hen DTC B0071 is set, go to DTC B0071 Chart.
For all other history codes refer to
“Diagnostic Aids” For that specific DTC.
A history DTC indicates the
malfunction has
been repaired or is intermittent. SRS is functional
and free of
malfunctions, no
further diagnosis is required.
If scan tool
indicated “NO DATA
RECEIVED,” refer to chassis
electrical section 8.

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ISUZU KB P190 2007

RESTRAINT CONTROL SYSTEM 9A1-9

Step Action Yes No
5 1. Ignition switch is at “LOCK”.
2. Connect a scan tool to data link connector.
3. Follow directions as given in the scan tool instruction manual.
4. Ignition switch is “ON”.
5. Request the SRS diagnostic trouble code display, Recode all diagnostic trouble code(s), specifying as current or history in
repair order.
Is (are) diagnostic trouble code (s) displayed? Ignition switch
“LOCK”.
W hen the current DTC is set, go to applicable DTC chart.
And then if DTC B0019, B0025,
B0051, B0055 or
B0071 is set, go to these DTC chart first.
W hen only history
DTCs exist, refer to “Diagnostics Aids” for that specific DTC.
A history DTC indicates the
malfunction has
been repaired or is intermittent. If scan tool indicates
“No Data Received,” refer to chassis
electrical section 8.


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ISUZU KB P190 2007

RESTRAINT CONTROL SYSTEM 9A1-11

3. W hen all circuitry outside the SRS control unit has been found to operate properly, as indicated by the
appropriate diagnostic chart, then and only then
should the SRS control unit be replaced.


Chart A SRS control unit Integrity Check
WARNING: DURING SERVICE PROCEDURES. BE VERY CAREFUL WHEN HANDLING A SRS CONTROL UNIT.
NEVER STRIKE OR JAR THE SRS CONTROL UNIT. NEVER POWER UP THE SRS WHEN THE SRS CONTROL
UNIT IS NOT RIGIDLY ATTACHED TO THE VEHICLE. ALL SRS CONTROL UNIT AND MOUNTING BRACKET
FASTENERS MUST BE CAREFULLY TORQUED AND THE ARROW MUST BE POINTING TOWARD THE FRONT
OF THE VEHICLE TO ENSURE PROPER OPERATION OF THE SRS. THE SRS CONTROL UNIT COULD BE
ACTIVATED WHEN POWERED WHILE NOT RIGIDLY ATTACHED TO THE VEHICLE WHICH COULD CAUSE
DEPLOYMENT AND RESULT IN PERSONAL INJURY
Step Action Yes No
1 1. This chart assumes that the “SRS Diagnostic System Check”
and either a symptom chart or a diagnostic trouble code chart
diagnosis has been performed. W hen all circuitry outside the
SRS control unit has been found to operate properly, as
indicated by the appropriate diagnostic chart, and the
symptom or DTC remains current, check the following.
2. Diagnostic procedures must be performed to verify the need
for SRS control unit replacement.
3. Ignition switch is at “LOCK”.
4. Reconnect all SRS components and ensure all components are properly mounted.
5. Ensure the ignition switch has been in the “LOCK” position for
at least 15 seconds.
6. Note the “SRS” warning lamp as the ignition switch is turned
“ON”.
Does the warning lamp flash 7 times then go “OFF”? The symptom or
DTC is no longer occurring.
Clear SRS
diagnostic trouble codes.
Repeat “SRS
Diagnostic System Check” Go to Step 2
2 Using a scan tool, request the diagnostic trouble code display.
Is the same symptom or DTC occurring that was occurring when
the “SRS Diagnostic System Check” was first performed? Go to Step 3 Ignition switch
“LOCK”.
Go to the
appropriate chart for the indicated malfunction.
3 1. Clear the “SRS Diagnostic Trouble Codes”.
2. Ignition switch is in the “LOCK” position for at least two
minutes.
3. Note the “SRS” warning lamp as the ignition switch is turned
“ON”.
Does warning lamp flash 7 times then go “OFF”? SRS is functional
and free of
malfunctions.
No further
diagnosis is required.
Go to Step 4 Ignition switch
“LOCK”.
Replace SRS control unit.
Go to Step 4
4 Reconnect all SRS components, ensure all components are properly mounted.
Is this step finished? Repeat the “SRS
Diagnostic System Check” —


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ISUZU KB P190 2007

RESTRAINT CONTROL SYSTEM 9A1-13

Chart B “SRS” warning lamp comes “ON” Steady

Step Action Yes No
1
1. W hen measurements are requested in this chart use a 5-
8840-0366-0DMM with correct terminal adapter from 5-8840-
0385-0.
2. Ignition switch is at “LOCK”.
3. Connect the scan tool to the data link connector, following
directions as given in the scan tool instruction MANUAL.
4. Ignition switch is “ON”.
5. Request the SRS diagnostic trouble code display.
Does the scan tool indicate “No Data Received”? Go to Step 2 Go to Step 3
2

1. Ignition switch is at “LOCK”.
2. Inspect the SRS control unit harness connector connection to
the SRS control unit.
Is it securely connected to the SRS control unit? Ignition switch
“LOCK”.
Replace SRS control unit.
Go to Step 5 Connect SRS
control unit
securely to de–
activate shorting
clip in SRS control unit harness connector.
Go to Step 5
3 Using scan tool, request the SRS data list.
Is “ignition” more than 9 volts? Go to Step 4 Ignition switch
“LOCK”.
Replace SRS control unit.
Go to Step 5
4
1. Ignition switch is at “LOCK”.
2. Disconnect the SRS coil and the passenger air bag assembly
yellow connector located at the base of the steering column
and behind the glove box assembly.
Disconnect the SRS control unit.
3. Disconnect the connector of the “SRS W arning Lamp” on the
instrument cluster.
4. Measure the resistance on the SRS control unit harness connector as follow.
z From terminals "3" and "23" to ground (ground) (without
the pretensioner)
z From terminals "3" and "15" to ground (ground) (with the
pretensioner and the passenger air bag)
z From terminals "3", "12" and "15" to ground (with the
pretensioner and without the passenger air bag)
Does 5-8840-0366-0DMM display “OL” (Infinite)? Go to Chart A Replace SRS
harness.
Go to Step 5
5 Reconnect all SRS components and ensure all components are
properly mounted.
Is this step finished? Repeat the “SRS
Diagnostic System Check” —


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9A1-24 RESTRAINT CONTROL SYSTEM

DTC Will Clear When
The “Passenger Bag Low" voltage comes to specified
voltage.

DTC Chart Test Description
Number(s) below refer to circled number(s) on the
diagnostic chart.
2. This test determines whether the SRS control unit is malfunctioning.
3. This test isolates the malfunction to one side of the passenger air bag assembly yellow connecto
r
behind the glove box compartment.


4. This test determines whether the malfunction is in
the “Passenger Bag High” circuit.
5. This test determines whether the malfunction is in the “Passenger Bag Low” circuit.

Diagnostic Aids
An intermittent condition is likely to be caused by a short
to ground/+B in the passenger air bag assembly circuit.
Inspect circuits “Passenger Bag High” and “Passenge
r
Bag Low” carefully for cutting or chafing. If the wiring
pigtail of the passenger air bag assembly is damaged,
the component must be replaced.

DTC B0018 (Flash Code 18) Passenger Air Bag Squib Circuit Short to GND

Step Action Yes No
1 W as the “SRS Diagnostic System Check” performed?
Go to Step 2 Go to the “SRS
Diagnostic System Check”
2 1. W hen measurements are requested in this chart use a 5-
8840-0366-0 DMM with a correct terminal adapter from 5-
8840-2835-0.
2. Ignition switch is at “LOCK”.
3. Ignition switch is “ON”.
4. Check the passenger air bag squib circuit for a short to ground.
W as a problem found? Go to Step 3

3 1. Ignition switch is at “LOCK”.
2. Disconnect the passenger air bag assembly yellow connector behind the glove box assembly.
3. Leave the driver air bag assembly connected.
4. Connect the SRS driver / passenger load tool 5-8840-2421-0 and appropriate adapter to the passenger air bag assembly
harness connector.
5. Ignition switch is “ON”.
Is DTC B0018 current? Go to Step 4 Ignition switch is at
“LOCK”.
Replace
passenger air bag assembly .
Go to Step 6
4 1. Ignition switch is at “LOCK”.
2. Disconnect the SRS driver /passenger load tool.
3. Measure the resistance on the SRS control unit harness connector as follow.
z From terminals "17" to "3" and "23" (ground) (without the
pretensioner)
z From terminals "17" to "3" and "15" (ground) (with the
pretensioner)
Does 5-8840-0366-0 display “OL” (Infinite)? Go to Step 5 Replace SRS
Harness.
Go to Step 6

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ISUZU KB P190 2007