Isuzu KB P190. Manual — part 1427

9A1-26 RESTRAINT CONTROL SYSTEM

DTC B0019 (Flash Code 19) Passenger Air Bag Squib Circuit Short to Battery
Voltage

RTW79ALF000301

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 the deployment loop voltages are
measured to ensure they are within their respective
normal voltage ranges.
The SRS control unit monitors the voltages at the
“Driver Bag Low” terminal “13” and “Passenger Bag
Low” terminal “16” to detect short to ground/+B in the air
bag assembly circuits.

DTC Will Set When

“Ignition 1" is in the normal operating voltage range.
The voltage at “Passenger Bag Low" is above a
specified value,
DTC B0019 will set.

Action Taken

The SRS control unit turns “ON” the “SRS” warning
lamp and sets a diagnostic trouble code.

RESTRAINT CONTROL SYSTEM 9A1-27

DTC Will Clear When

The SRS control unit is replaced and 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 connector
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 “Passenger
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 B0019 (Flash Code 19) Passenger Air Bag Squib Circuit Short to Battery Voltage

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 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

voltage, short to ground and open.

Was 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 B0019 current?

Go to Step 4

Ignition switch is at

“LOCK”.
Replace

passenger air bag

assembly

Go to Step 6

4

Measure the resistance on the SRS control unit harness
connector from terminal “17” to terminal “1” (ignition).

Does 5-8840-0366-0 display “OL” (Infinite)?

Go to Step 5

Replace SRS

Harness.

Go to Step 6

5

Measure the resistance on the SRS control unit harness
connector from terminal “16” to terminal “1” (ignition).

Does 5-8840-0366-0 display “OL” (Infinite)?

Go to Chart A

Replace SRS

Harness.

Go to Step 6

6

1. Reconnect all the components and ensure all components

are properly mounted.

2. Clear diagnostic trouble codes.
Is this step finished?

Go to the “SRS

Diagnostic system

Check”

―

9A1-28 RESTRAINT CONTROL SYSTEM

DTC B0021 (Flash Code 21) Driver Air Bag Squib Circuit High Resistance

RTW79ALF000301

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 “13” is grounded through a current sink and the
driver current source connected to “Driver Bag High”
terminal “14” 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 air bag
assembly, SRS coil assembly, harness wiring circuits
“Driver Bag High” and “Driver Bag Low” and connector
terminal contact.

RESTRAINT CONTROL SYSTEM 9A1-29

DTC Will Set When

The combined resistance of the driver air bag
assembly, the SRS Coil assembly, the harness wiring
circuits “Driver Bag High” and “Driver Bag Low”, and
connector terminal contact is above a specified value.
This test runs once for 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

The SRS control unit turns “ON” the “SRS” warning
lamp and sets DTC B0021.

DTC Will Clear When

Resistance value returns to specified resistance value.

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 the steering
column.

5. This test isolates 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, the SRS control unit
terminals “14” and “13” or a poor wire to terminal
connection in circuit “Driver Bag High” or “Driver Bag
Low” The test for this diagnostic trouble code is only run
while the “SRS” 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 B0021 (Flash Code 21) Driver Air Bag 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 a the problem is found, repair as necessary.
Was a problem found?

Verify repair

Go to Step 3

3

1. Ignition switch to “LOCK”.

2. Disconnect the SRS coil assembly yellow connector located

at the base of the steering column and check it is seated
properly.

Is the connector connected properly?

Go to Step 4

Seat SRS coil

assembly

connector properly.

Go to Step 8