2004 ISUZU TF SERIES ESP

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 9A1-29

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”.

9A1-32 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 9A1-39

DTC B0053 (Flash Code 53) Deployment Command Despite Present Trouble
Code


RTW49JLF000101

Circuit Description
The SRS control unit contains a sensor which converts
vehicle velocity changes to an electrical signal. The
electrical signal generated is processed by the SRS
control unit and then compared to a value stored in
memory. When the generated signal exceeds the
stored value, the SRS control unit will cause current to
flow through the air bag assembly deploying the ai
r
bags. DTC B0053 is set accompanying with DTC
B0051 when a deployment occurs while an air bag
assembly circuit fault is present that could possible
result in a no deployment situation in one or both air bag
assemblies.


DTC Will Set When
The SRS control unit detects a frontal crash, up to 30
degrees off the centerline of the vehicle, of sufficient
force to warrant deployment of the air bags and an
inflator circuit fault is present.

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

DTC Will Clear When
The SRS control unit is replaced.

9A1-40 RESTRAINT CONTROL SYSTEM

DTC Chart Test Description
Number(s) below refer to step number(s) on the
diagnostic chart:
2.
If air bag assembly have not deployed, DTC B0053
may have falsely set.
3.
If DTC B0053 has set with no signs of frontal impact,
the diagnostic trouble code has falsely set.


DTC B0053 (Flash Code 53) Deployment Command Despite Present Trouble Code
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 Was the “SRS Diagnostic System Check” performed? Go to Step 2 Go to the “SRS
Diagnostic System
Check”
2 Ignition switch “OFF.”
Have air bag assembles deployed? Replace
components and
perform
inspections as
directed in
“Repairs And
Inspections
Required After An
Accident” in this
section.
Clear diagnostic
trouble codes.
Repeat the “SRS
Diagnostic System
Check” Go to Step 3
3 Inspect front of vehicle and undercarriage for signs of impact.
Were signs of impact found? Replace
components and
perform
inspections as
directed in
“Repairs And
Inspections
Required After An
Accident” in this
section.
Clear diagnostic
trouble codes.
Repeat “SRS
Diagnostic System
Check” Ignition switch
“OFF.”
Replace SRS
control unit.
Reconnect all SRS
system
components,
ensure all
components are
properly mounted.
Repeat the “SRS
Diagnostic System
Check”

RESTRAINT CONTROL 9A1-41

DTC B0057 (Flash Code 57) Passenger Pretensioner 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”.
“Passenger Pretensioner Low” terminal “43” is
grounded through a resistor and the passenger current
source connected to “Passenger Pretensioner High”
terminal “44” allows a known amount of current to flow.

By monitoring the voltage difference between
“Passenger Pretensioner High” and “Passenger
Pretensioner Low”, the SRS control unit calculates the
combined resistance of the passenger air bag
assembly, harness wiring circuits “Passenger
Pretensioner High” and “Passenger Pretensioner Low”
connector terminal contact.

9A1-44 RESTRAINT CONTROL SYSTEM

DTC B0058 (Flash Code 58) Passenger Pretensioner 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”.
“Passenger Pretensioner Low” terminal “43” is
grounded through a resister and the passenger current
source connected to “Passenger Pretensioner High”
terminal “44” allows a known amount of current to flow.
By monitoring the voltage difference between
“Passenger Pretensioner High” and “Passenger
Pretensioner Low” the SRS control unit calculates the
combined resistance of the passenger pretensione
r
assembly, harness wiring circuits “Passenger
Pretensioner High” and “Passenger Pretensioner Low”
connector terminal contact.

RESTRAINT CONTROL 9A1-47

DTC B0059 (Flash Code 59) Passenger Pretensioner 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 pretensioner loop voltages are
measured to ensure they are within their respective
normal voltage ranges.
The SRS control unit monitors the voltages at “Drive
r
Pretensioner Low” terminal “41” and “Passenger
Pretensioner Low” terminal “43” to detect short to
ground/+B in the pretensioner assembly circuits.

DTC Will Set When
Neither of the air bag and the pretensioner are belt
open. “Ignition 1” is within the normal operating voltage
range. Once these conditions are met and the voltage
at “Passenger Pretensioner Low” is out of a specified
value, DTC B0059 will set. This test is run once each
ignition cycle and “Continuous Monitoring”.

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