Isuzu Trooper (1998-2002 year). Manual - part 1099

9J1–33

RESTRAINT CONTROL SYSTEM

DTC 26  Driver Deployment Loop Open

D09RW014

Circuit Description:

When the ignition switch is turned “ON”, the SDM 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.
During “Continuous Monitoring” diagnostics, a fixed
amount of current is following in the deployment loop.
This produces proportional voltage drops in the loop.  By
monitoring the voltage difference between “Driver Bag
High” and “Driver Bag Low”, the SDM calculates the
combined resistance of the driver air bag assembly, SRS
coil assembly, harness wiring IB05–YEL and
IB06–YEL/BLK, and connector terminal contact.

DTC Will Set When:

The voltage difference between “Driver Bag High”
terminal “3” and “Driver Bag Low” terminal “4” is above or
equal to a specified value for 500 milliseconds during
“Continuous Monitoring”.

Action Taken:

SDM turns “ON” the “AIR BAG” warning lamp and sets a
diagnostic trouble code.

DTC Will Clear When:

The voltage difference between “Driver Bag High”
terminal “3” and “Driver Bag Low” terminal “4” is below a

specified value for 500 milliseconds during “Continuous
Monitoring”.

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 SDM.

3. This test verifies proper connection of the yellow

2–pin connector at the base of the steering column.

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

of the yellow 2–pin connector at the base of the
steering column.

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

SRS coil assembly yellow 2–pin connector located
at the base of steering column.

6. This test determines whether the open is 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 the driver air bag assembly harness 2–pin
connector terminals “1” and “2” at the top of the steering
column, SRS coil assembly harness 2–pin connection
terminals “1” and “2”, SDM terminals “3” and “4”, or an
open in IB05–YEL and IB06–YEL/BLK.

RESTRAINT CONTROL SYSTEM

9J1–34

DTC 26 Driver Deployment Loop Open 

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

5–8840–0285–0 DVM with correct terminal adapter from
5–8840–0385–0. 

2. Use scan tool data list function, read and record the driver

differential voltage.

Is driver VDIF more than 4.25 volts?

Go to Step 3

Go to Chart A

3

1. Ignition switch “OFF.”
2. Make sure the SRS coil assembly yellow 2–pin connector

located at the base of steering column is seated properly.

Is the yellow 2–pin connector connected properly?

Go to Step 4

Seat driver air

bag assembly

2–pin connector

Go to Step 8

4

1. Disconnect and inspect the SRS coil assembly yellow 2–pin

connector located base of steering column.

2. If ok, reconnect the SRS coil assembly yellow 2–pin

connector.

3. Ignition switch “ON.”

Is DTC 26 current?

Go to Step 5

Go to Step 8

5

1. Ignition switch “OFF”.
2. Disconnect SRS coil and passenger air bag assembly, yellow

2–pin connectors located at the base of steering column and
behind the glove box assembly.

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

appropriate adapter to SRS coil and passenger  air bag
assembly harness connectors.

4. Ignition switch “ON.”

Is DTC 26 current?

Go to Step 6

Go to Step 7

6

1. Ignition switch “OFF.”
2. There has been an open circuit in the driver inflator

deployment loop.

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

checking IB05–YEL and IB06–YEL/BLK, and SDM connector
terminal “3” and “4” to locate the root cause.

Was a fault found?

Replace SRS

harness

Go to Step 8

Go to Chart A

7

1. Ignition switch “OFF.”
2. Disconnect SRS driver / passenger load tool from SRS coil

assembly harness connector.

3. Connect SRS driver / passenger load tool 5–8840–2421–0 on

steering column 2–pin connector.

4. Reconnect SRS coil assembly harness connector at the base

of steering column.

5. Ignition switch “ON.”

Is DTC 26 current?

Ignition switch

“OFF”

Replace SRS coil

assembly

Go to Step 8

Ignition switch

“OFF”

Replace driver air

bag 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” 

Go to Step 8

9J1–35

RESTRAINT CONTROL SYSTEM

DTC 51  Air Bag Deployment Event Commanded

D09RW014

Circuit Description:

The SDM contains a sensing device which converts
vehicle velocity changes to an electrical signal.  The
electrical signal generated is processed by the SDM and
then compared to a value stored in memory.  When the
generated signal exceeds the stored value, the SDM will
cause current to flow through the air bag assembly
deploying the air bags and causing DTC 51 to set.

DTC Will Set When:

The SDM detects a frontal crash, up to 30 degrees off the
centerline of the vehicle, of sufficient force to warrant
deployment of the air bags.

Action Taken:

SDM turns “ON” the “AIR BAG” warning lamp records
“Crash Data”, and sets a diagnostic trouble code.

DTC Will Clear When:

The SDM is replaced.

DTC Chart Test Description:

Number(s) below refer to step number(s) on the
diagnostic chart:
2. If air bag assembly (s) has not deployed, DTC 51

may have falsely set.

3. If DTC 51 has set with no signs of frontal impact, the

diagnostic trouble code has falsely set.

RESTRAINT CONTROL SYSTEM

9J1–36

DTC 51  Air Bag Deployment Event Commanded 

WARNING: DURING SERVICE PROCEDURES. BE VERY CAREFUL WHEN HANDLING A SENSING AND
DIAGNOSTIC MODULE (SDM). NEVER STRIKE OR JAR THE SDM.  NEVER POWER UP THE SRS WHEN THE
SDM IS NOT RIGIDLY ATTACHED TO THE VEHICLE. ALL SDM AND MOUNTING BRACKET FASTENERS MUST
BE CAREFULLY TORQUED AND THE ARROW MUST BE POINTING TOWARD THE FRONT OF THE VEHICLE
TO ENSURE PROPER OPERATION OF THE SRS. THE SDM COULD BE ACTIVATED WHEN POWERED WHILE
NOT RIGIDLY ATTACHED TO THE VEHICLE WHICH COULD CAUSE DEPLOYMENT AND RESULT IN
PERSONAL INJURY.

Step

Action

Yes

No

1

Was the “SRS Diagnostic System Check” performed?

Go to Step 2

Go to the “SRS

Diagnostic

System Check”

2

Ignition switch “OFF.”

Have air bag assemblies deployed?

Replace

components and

perform

inspections as

directed in

“repairs and

inspections

required after an

accident” in this

section

Clear diagnostic

trouble codes

Repeat “SRS

Diagnostic

System Check”

Go to Step 3

3

Inspect front of vehicle and undercarriage for sings of impact.

Were signs of impact found?

Replace

components and

perform

inspections as

directed in

“Repairs and

Inspections

Required After An

Accident” in this

section

Clear diagnostic

trouble codes

Repeat “SRS

Diagnostic

System Check”

Ignition switch

“OFF”

Replace SDM

Reconnect all

SRS system

components,

ensure all

components are

properly mounted

Repeat “SRS

Diagnostic

System Check”