Isuzu KB P190. Manual - part 1434

9A1-54  RESTRAINT CONTROL SYSTEM 

 

DTC B0042 (Flash Code 42) Driver Pretensioner 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 Pretensioner 
Low” terminal “7” is grounded through a current sink 
and the driver current source connected to “Driver
Pretensioner High” terminal “8” allows a known amount 
of current to flow. By monitoring the voltage difference
between “Driver Pretensioner High” and “Driver 
Pretensioner Low”, the SRS control unit calculates the
combined resistance of the driver pretensioner
assembly, SRS coil assembly, harness wiring circuits
“Driver Pretensioner High” and “Driver Pretensioner
Low” and connector terminal contact. 
 

RESTRAINT CONTROL SYSTEM  9A1-55 

 

DTC Will Clear When 

The ignition switch is turned “LOCK”. 
 

DTC Will Set When 

The combined resistance of the driver pretensioner
assembly, harness wiring circuits “Driver Pretensioner
High” and “Driver Pretensioner 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 B0042. 
 

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 driver seat. 

4.  This test checks for proper contact and/or corrosion

of the connector terminals at the base of the driver 
seat. 

5.  This test isolate the malfunction to one side of the

SRS coil assembly yellow connector located at the
base of the driver seat. 

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 driver pretensioner assembly. 

 

 

Diagnostic Aids 

An intermittent condition is likely to be caused by a poor 
connection at the drive pretensioner harness connector 
terminals “1” and “2”, SRS control unit terminals “8” and 
“7”, or a poor wire to terminal connection in circuit 
“Driver Pretensioner High” or “Driver Pretensioner Low” 
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 B0042 (Flash Code 42) Driver Pretensioner 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 pretensioner 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 is at “LOCK”. 

 2. Disconnect SRS coil assembly yellow connector located at 

base of the driver seat. 

Is the connector connected properly? 

Go to Step 4 

Seat pretensioner 

assembly 

connector 

properly. 

Go to Step 8 

9A1-56  RESTRAINT CONTROL SYSTEM 

 

Step Action 

Yes 

No 

4  

 1. Disconnect and inspect the pretensioner assembly yellow 

connector located base of the driver seat. 

 2. If ok, reconnect the pretensioner yellow connector. 

 3. Ignition switch is at “ON”. 
Is DTC B0042 current? 

Go to Step 5 

Go to Step 8 

5  

 1. Ignition switch is at “LOCK”. 

 2. Disconnect diver pretensioner assembly, yellow connector 

located at the base of driver seat. 

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

appropriate adapter to driver pretensioner assembly harness 
connectors. 

 4. Ignition switch is at “ON”. 
Is DTC B0042 current? 

Go to Step 6 

Go to Step 7 

6  

 1. Ignition switch is at “LOCK“. 

 2. There has been a increase in the total circuit resistance of the 

driver deployment loop. 

 3. Use the high resolution ohmmeter mode of the DVM while 

checking circuits “Driver Pretensioner High” and “Driver 
Pretensioner Low”, and SRS control unit connector terminal 
“8” and “7” to locate the root cause. 

Was a fault found? 

Replace 

pretensioner 

harness. 

Go to Step 8 

Go to Chart A  

7  

 1. Ignition switch is at “LOCK”. 

 2. 

Disconnect pretensioner load tool from pretensioner 
assembly harness connector. 

 

3. 

Connect pretensioner load tool 5-8840-2421-0 and 
appropriate adapter to driver pretensioner assembly harness 
connector. 

 4. Reconnect pretensioner harness connector as the base of the 

driver seat. 

 5. Ignition switch is at “ON”. 
Is DTC B0065 current? 

Ignition switch is at 

“LOCK”. 
Replace 

pretensioner 

assembly. 

Go to Step 8 

Ignition switch is at 

“LOCK”. 

Replace driver 

pretensioner 

assembly. 

Go to Step 8 

8  

 1. Reconnect all components ensure all component are properly 

mounted. 

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

Repeat the “SRS 

Diagnostic System 

Check” 

― 

 

 

RESTRAINT CONTROL SYSTEM  9A1-57 

 

DTC B0045 (Flash Code 45) Driver Pretensioner 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 pretensioner loop voltages are
measured to ensure they are within their respective
normal voltage ranges. 
The SRS control unit monitors the voltages at “Driver
Pretensioner Low” terminal “7” and “Passenger 
Pretensioner Low” terminal “10” to detect short to
ground/+B in the pretensioner assembly circuits. 
 

 

DTC Will Set When 

“Ignition 1" is in the normal operating voltage range. 
The voltage at “Driver Pretensioner Low " is below a 
specified value, 
DTC B0045 will set. 
 

Action Taken 

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