airbag ISUZU TF SERIES 2004 User Guide

9A1-26 RESTRAINT CONTROL SYSTEM

DTC B0022 (Flash Code 22) Driver Airbag Squib Circuit Low Resistance


RTW49JLF000101

Circuit Description
When the ignition switch is turned “ON”, the SRS
control unit will perform tests to diagnose critical
malfunctions within itself. Upon passing these tests
“Ignition 1”, and deployment loop voltages are
measured to ensure they are within their respective
normal voltage ranges.
The SRS control unit then proceeds with the
“Resistance Measurement Test” “Driver Bag Low”
terminal “46” is grounded through a current sink and
the driver current source connected to “Driver Bag
High” terminal “45” allows a known amount of current to
flow. By monitoring the voltage difference between
“Driver Bag High” and “Driver Bag Low” the SRS control
unit calculates the combined resistance of the driver ai
r
bag assembly, SRS coil assembly, harness wiring
circuits “Driver Bag High” and “Driver Bag Low” and
connector terminal contact.

RESTRAINT CONTROL 9A1-27

DTC Will Set When
The combined resistance of the driver air bag
assembly, SRS Coil assembly, harness wiring circuits
“Driver Bag High” and “Driver Bag Low”, and connector
terminal contact is above a specified value. This test is
run once each ignition cycle during the “Resistance
Measurement Test” when:
1.
No “higher priority faults” are detected during “Turn–
ON”
2.
“Ignition 1” voltage is in the specified value.

Action Taken
SRS control unit turns “ON” the “AIR BAG” warning
lamp and sets DTC B0022.

DTC Will Clear When
The ignition switch is turned “OFF.”
DTC Chart Test Description
Number(s) below refer to circled number(s) on the
diagnostic chart:
2.
This test determines whether the malfunction is in
the SRS control unit.
3.
This test verifies proper connection of the yellow
connector at the base of the steering column.
4.
This test checks for proper operation of the shorting
clip in the yellow connector.
5.
This test isolate the malfunction to one side of the
SRS coil assembly yellow connector located at the
base of steering column.
6.
This test determines whether the malfunction is due
to shortening in the wiring.
7.
This test determines whether the malfunction is in
the SRS coil assembly or the driver air bag
assembly.

Diagnostic Aids
An intermittent condition is likely to be caused by a short
between circuit “Driver Bag High” or “Driver Bag Low”
or a malfunctioning shorting clip on the driver air bag
assembly or SRS coil assembly which would require
replacement of the component. The test for this
diagnostic trouble code is only run while the “AIR BAG”
warning lamp is performing the bulb check. When a
scan tool “Clear Codes” command is issued and the
malfunction is still present, the DTC will not reappear
until the next ignition cycle.


DTC B0022 (Flash Code 22) Driver Airbag Squib Circuit Low Resistance

Step Action Yes No
1 Perform the “SRS Diagnostic System Check.”
Was the “SRS Diagnostic System Check” performed? Go to Step 2 Go to the “SRS
Diagnostic System
Check”
2

1. Check the driver air bag squib circuit for short to voltage or
short to ground.

2. If the problem found, repair as necessary.
Was a problem found? Verify repair Go to Step 3
3

1. Ignition switch “OFF.”

2. Make sure the SRS coil assembly yellow connector located
at the base of steering column is seated properly.
Is the connector connected properly? Go to Step 4 Seat driver air bag
assembly
connector
properly.
Go to Step 8
4

1. Disconnect and inspect the SRS coil assembly yellow
connector located base of steering column.

2. If ok, reconnect the SRS coil assembly yellow connector.

3. Ignition switch “ON.”
Is DTC B0022 current? Go to Step 5 Go to Step 8

RESTRAINT CONTROL 9A1-29

DTC B0024 (Flash Code 24) Driver Airbag Squib Circuit Voltage
Range/Performance


RTW49JLF000101
Circuit Description
When the ignition switch is turned “ON”, the SRS
control unit will perform tests to diagnose critical
malfunctions within itself. Upon passing these tests,
“Ignition 1”, and deployment loop voltages are
measured to ensure they are within their respective
normal voltage ranges.
The SRS control unit monitors the voltage at “Drive
r
Bag Low” terminal “46” and “Passenger Bag Low”
terminal “47” to detect shorts to ground/+B in the air bag
assembly circuits.


DTC Will Set When
Neither of the two air bag assemblies is open.
“Ignition 1” is within the normal operating voltage range.
This test is run once each ignition cycle and
“Continuous Monitoring”. Once these conditions are
met and the voltage at “Driver Bag Low” is out of a
specified value, DTC B0024 will set.

Action Taken
SRS control unit turns “ON” the “AIR BAG” warning
lamp and sets a diagnostic trouble code.

DTC Will Clear When
The malfunction is no longer occurring and the ignition
is turned “OFF”.

9A1-30 RESTRAINT CONTROL SYSTEM

DTC Chart Test Description
Number(s) below refer to step 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
SRS coil assembly yellow 2–pin connector at the
base of the steering column.
4.
This test determines whether the malfunction is in
“Driver Bag High” circuit.
5.
This test determines whether the malfunction is in
“Driver Bag Low” circuit.
6.
This test determines whether the malfunction is in
“Driver Bag High” circuit.
7.
This test determines whether the malfunction is in
“Driver Bag Low” circuit.
8.
This test determines whether the malfunction is in
the SRS coil assembly or the driver air bag
assembly.
Diagnostic Aids
An intermittent condition is likely to be caused by a short
to ground/+B in the driver air bag assembly circuit.
Inspect circuits “Driver Bag High” and “Driver Bag Low”
carefully for cutting or chafing.


DTC B0024 (Flash Code 24) Driver Airbag Squib Circuit Voltage Range/Performance

Step Action Yes No
1 Was the “SRS Diagnostic System Check” performed? Go to Step 2 Go to the “SRS
Diagnostic System
Check”
2

1. When measurements are requested in this chart use 5-8840-
0285-0 DVM with correct terminal adapter from 5-8840-
0385-0.

2. Ignition switch “OFF.”
3. Ignition switch “ON.”

4. Check the driver air bag squib circuit for short to voltage or
short to ground and open.
Was a problem found? Go to Step 3


3

1. Ignition switch “OFF.”

2. Disconnect SRS coil assembly yellow connector located at
base of the steering column. leave passenger air bag
assembly connected.

3. Connect SRS driver / passenger load tool 5-8840-2421-0 and
appropriate adapter to SRS coil assembly harness
connector.

4. ignition switch “ON.”
Is DTC B0024 current? Go to Step 4 Go to Step 8
4

1. Ignition switch “OFF.”

2. Disconnect SRS control unit.
3. Disconnect SRS driver / passenger load tool.

4. Measure resistance on SRS control unit harness connector
“45” to terminal “40” (ground).
Does 5-8840-0285-0 display “OL” (infinite)? Go to Step 5 Replace SRS
harness.
Go to Step 9
5 Measure resistance on SRS control unit harness connector from
terminal “46” to terminal “40” (ground).
Does 5-8840-0285-0 display “OL” (infinite)? Go to Step 6
Replace SRS
harness.
Go to Step 9

9A1-32 RESTRAINT CONTROL SYSTEM

DTC B0026 (Flash Code 26) Driver Airbag Squib Circuit High Resistance


RTW49JLF000101

Circuit Description
When the ignition switch is turned “ON”, the SRS
control unit will perform tests to diagnose critical
malfunctions within itself. Upon passing these tests,
“Ignition 1”, and deployment loop voltages are
measured to ensure they are within their respective
normal voltage ranges.
The SRS control unit then proceeds with the
“Resistance Measurement Test” “Driver Bag Low”
terminal “46” is grounded through a current sink and the
driver current source connected to “Driver Bag High”
terminal “45” allows a known amount of current to flow.
By monitoring the voltage difference between “Drive
r
Bag High” and “Driver Bag Low”, the SRS control unit
calculates the combined resistance of the driver air bag
assembly, SRS coil assembly, harness wiring circuits
“Driver Bag High” and “Driver Bag Low” and connecto
r
terminal contact.

RESTRAINT CONTROL 9A1-33

DTC Will Set When
The combined resistance of the driver air bag
assembly, SRS Coil assembly, harness wiring circuits
“Driver Bag High” and “Driver Bag Low”, and connector
terminal contact is above a specified value. This test
run once each ignition cycle during the “Resistance
Measurement Test” when:
1.
No “higher priority faults” are detected during “Turn–
ON”
2.
“Ignition 1” voltage is in the specified value.

Action Taken
SRS control unit turns “ON” the “AIR BAG” warning
lamp and sets DTC B0026.

DTC Will Clear When
The ignition switch is turned “OFF”.



DTC Chart Test Description
Number(s) below refer to step number(s) on the
diagnostic chart:
2.
This test determines whether the malfunction is in
the SRS control unit.
3.
This test verifies proper connection of the yellow
connector at the base of the steering column.
4.
This test checks for proper contact and/or corrosion
of the connector terminals at the base of steering
column.
5.
This test isolate the malfunction to one side of the
SRS coil assembly yellow connector located at the
base of the steering column.
6.
This test determines whether the malfunction is due
to high resistance in the wiring.
7.
This test determines whether the malfunction is in
the SRS coil assembly or the driver air bag
assembly.

Diagnostic Aids
An intermittent condition is likely to be caused by a poor
connection at terminals “1” and “2” of the SRS coil
connector at the base of the steering column, terminal
“1” and “2” of the driver air bag assembly connector at
the top of the steering column, SRS control unit
terminals “45” and “46” or a poor wire to terminal
connection in circuit “Driver Bag High” or “Driver Bag
Low” The test for this diagnostic trouble code is onl
y
run while the “AIR BAG” warning lamp is performing
the bulb check. When a scan tool “Clear Codes”
command is issued and the malfunction is still present,
the DTC will not reappear until the next ignition cycle.

DTC B0026 (Flash Code 26) Driver Airbag Squib Circuit High Resistance

Step Action Yes No
1 Perform the “SRS Diagnostic System Check”.
Was the “SRS Diagnostic System Check” performed? Go to Step 2 Repeat the “SRS
Diagnostic System
Check”
2

1. Check the driver air bag squib circuit for open.

2. If the problem found, repair as necessary.
Was a problem found? Verify repair Go to Step 3
3

1. Ignition switch “OFF.”

2. Disconnect SRS coil assembly yellow connector located at
base of steering column is seated properly.
Is the connector connected properly? Go to Step 4 Seat SRS coil
assembly
connector
properly.
Go to Step 8

RESTRAINT CONTROL 9A1-59

DTC B0670 (Flash Code 63) Airbag Telltale Circuit Malfunction


RTW49JLF000101

Circuit Description
When the ignition switch is turned “ON”, battery voltage
is applied to the “AIR BAG” warning lamp and to the
“Ignition 1” input terminal “35”. The SRS control unit
responds by flashing the “AIR BAG” warning lamp
seven times. The SRS control unit monitors the lamp
driver output by comparing the output state at “SRS
Warning Lamp” terminal “39” to the microprocesso
r
commanded state. When “Ignition 1” is in the specified
value, and the output state does not match the
commanded state of the lamp driver for 500
milliseconds, DTC B0670 is set.


DTC Will Set When
“Ignition 1” voltage is in the specified value and the
output state at the “SRS Warning Lamp” terminal does
not match the commanded state of the lamp driver for
500 milliseconds. This test is run every 100
milliseconds during “Continuous Monitoring” tests and
once per each ignition cycle at the beginning.

Action Taken
SRS control unit attempts to turn “ON” the “AIR BAG”
warning lamp and sets a diagnostic trouble code.

DTC Will Clear When
The ignition switch is turned “OFF.”

9A1-60 RESTRAINT CONTROL SYSTEM

DTC Chart Test Description
Refer to Charts B and C to diagnose warning lamp
circuit malfunctions.


DTC B0670 (Flash Code 63) Airbag Telltale Circuit Malfunction

Step Action Yes No
1 Was the “SRS Diagnostic System Check” performed? Go to Step 2 Go to the “SRS
Diagnostic System
Check”
2

1. Malfunctions within the “AIR BAG” warning lamp circuitry will
set this diagnostic trouble code.

2. These malfunctions are addressed in the “SRS Diagnostic
System Check” via Chart B and Chart C.
3. Failure to properly perform the “SRS Diagnostic System
Check” may result in misdiagnosis.

4. Ignition switch “ON.”

5. Clear SRS diagnostic trouble codes.
Is DTC B0670 set? Ignition switch
“OFF.”
Go to Chart A Repeat the “SRS
Diagnostic System
Check”