Isuzu KB P190. Manual — part 1429

9A1-34 RESTRAINT CONTROL SYSTEM

DTC B0025 (Flash Code 25) Driver Air Bag Squib Circuit Short to GND

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 monitors the voltage at “Driver
Bag Low” terminal “13” and “Passenger Bag Low”
terminal “16” to detect shorts to ground/+B in the air bag
assembly circuits.

DTC Will Set When

“Ignition 1" is within the normal operating voltage range.
The voltage at “Driver Bag Low" is below a specified
value DTC B0025 will set.

Action Taken

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

DTC Will Clear When

The “Driver Bag Low" voltage comes to specified
voltage.

RESTRAINT CONTROL SYSTEM 9A1-35

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

the “Driver Bag High” circuit.

5. This test determines whether the malfunction is in

the “Driver Bag Low” circuit.

6. 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 B0025 (Flash Code 25) Driver Air Bag Squib Circuit Short to GND

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 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 is at “LOCK”.

2. Disconnect the SRS coil assembly yellow connector located

at base of the steering column. Leave the passenger air bag
assembly connected.

3. Connect the SRS driver /passenger load tool 5-8840-2421-0

and appropriate adapter to the SRS coil assembly harness
connector.

4. Ignition switch is “ON”.
Is DTC B0025 current?

Go to Step 4

Go to Step 6

4

1. Ignition switch is at “LOCK”.

2. Disconnect the SRS control unit.

3. Disconnect the SRS driver /passenger load tool.

4. Measure the resistance on the SRS control unit harness

connector as follow.

From terminals "14" to "3" and "23" (ground) (without the

pretensioner)

From terminals "14" to "3" and "15" (ground) (with the

pretensioner and the passenger air bag)

From terminals "14" to "3", "12" and "15" (ground) (with

the pretensioner and without the passenger air bag)

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

Go to Step 5

Replace SRS

harness.

Go to Step 7

9A1-36 RESTRAINT CONTROL SYSTEM

Step Action

Yes

No

5

Measure the resistance on the SRS control unit harness
connector as follow.

From terminals "13" to "3" and "23" (ground) (without the

pretensioner)

From terminals "13" to "3" and "15" (ground) (with the

pretensioner and the passenger air bag)

From terminals "13" to "3", "12" and "15" (ground) (with

the pretensioner and without the passenger air bag)

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

Go to Chart A

Replace SRS

harness.

Go to Step 7

6

1. Ignition switch is at “LOCK”.

2. Disconnect the SRS driver /passenger load tool 5-8840-2421-

0 from the SRS coil assembly harness connector.

3. Connect the SRS driver /passenger load tool 5-8840-2421-0

and appropriate adapter to the driver air bag assembly
harness connector. located at top of the steering column
connector.

4. Reconnect the SRS coil assembly harness connector at the

base of the steering column.

5. Ignition switch is “ON”.
Is DTC B0025 current?

Ignition switch is at

“LOCK”.

Replace SRS coil

assembly.

Go to Step 7

Ignition switch is at

“LOCK”.

Replace driver air

bag assembly.

Go to Step 7

7

1. Reconnect all components and ensure all components are

properly mounted.

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

Go to the “SRS

Diagnostic System

Check”

―

RESTRAINT CONTROL SYSTEM 9A1-37

DTC B0026 (Flash Code 26) Driver 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 deployment loop voltages are
measured to ensure they are within their respective
normal voltage ranges.
The SRS control unit monitors the voltage at “Driver
Bag Low” terminal “13” and “Passenger Bag Low”
terminal “16” to detect shorts 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 “Driver Bag Low" is above a specified
value,
DTC B0026 will set.

Action Taken

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

DTC Will Clear When

The SRS control unit is replaced and the “Driver Bag
Low" voltage comes to specified voltage.