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.