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.