Isuzu Trooper (1998-2002 year). Manual - part 1101

9J1–41

RESTRAINT CONTROL SYSTEM

DTC 71  Internal SDM Fault

D09RW014

Circuit Description:

DTC 71 is an indication of a potential internal SDM
malfunction and will set if any of the following conditions
are detected:
1) Deployment or microprocessor energy reserve failure.
2) EEPROM failure.
3) ROM failure.
4) RAM failure.
5) Calibration check sum failure.
6) Deployment switch faults.
7) Accelerometer fault.
8) Arming sensor fault.
9) Diagnostic current faults.
10) DTC 19
11) DTC 25
12) DTC 51
13) DTC 53

DTC Will Set When:

Any of the above indicated malfunctions are detected by
the SDM.  The malfunctions described above are tested
mainly during “Continuous Monitoring” and some ones
run each ignition cycle.

Action Taken:

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

DTC Will Clear When:

A scan tool “Clear Codes” commanded is received by the
SDM.  Some of the indicated malfunctions will only allow
the “AIR BAG” warning lamp to go out.
But when DTC 19, 25, 51, 53 are also set, SDM is
replaced.

RESTRAINT CONTROL SYSTEM

9J1–42

DTC 71 Internal SDM Fault 

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.

CAUTION: When DTC 19 or 25 has been set, it is necessary to replace the SDM.  Setting DTC 19 and 25 or 51
or 53 will also cause DTC 71 to set.  When a scan tool “CLEAR CODES” command is issued and the
malfunction is no longer present, DTC 51 or 53 and DTC 71 will remain current.  Ensure that the short to voltage
condition DTC 19, 25 is repaired prior to installing a replacement SDM to avoid damaging the SDM. 

Step

Action

Yes

No

1

Was the “SRS Diagnostic System Check” performed?

Go to Step 2

Go to the “SRS

Diagnostic

System Check”

2

Note SRS “Diagnostic System Check.”

IS DTC 19 OR 25 OR 51 OR 53 ALSO SET (CURRENT OR
HISTORY)? (REFER TO NOTICE ABOVE.)

Go to DTC 19 if

DTC 19 is set

Go to DTC 25 if

DTC 25 is set

Go to DTC 51 if

DTC 51 is set

Go to DTC 53 if

DTC 53 is set

Ignition switch

“OFF”

Replace SDM

Repeat the “SRS

Diagnostic

System Check”

9J1–43

RESTRAINT CONTROL SYSTEM

DTC 29  Passenger Pretensioner Loop Short To Ground

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
pretensioner loop voltages are measured to ensure they
are within their respective normal voltage ranges.
The SDM monitors the voltages at “Driver Belt Low”
terminal “10” and “Passenger Belt Low” terminal “22” to
detect short to ground in the pretensioner assembly
circuits.

DTC Will Set When:

Neither of the air bag and the pretensioner belt are open.
“Ignition 1” is within the normal operating voltage range.
Once these conditions are met and the voltage at
“Passenger Belt Low” is below a specified value, DTC 29
will set.  This test is run once each ignition cycle and
“Continuous Monitoring”.

Action Taken:

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

DTC Will Clear When:

This malfunction is no longer occurring and the ignition
switch is turned “OFF”.

DTC Chart Test Description:

Number(s) below refer to circled number(s) on the
diagnostic chart.
2. This test determines whether the SDM is

malfunctioning.

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

passenger pretensioner assembly yellow 2–pin
connector at the base of the passenger seat.

4. This test determines whether the malfunction is in

IB15–BLU/BLK.

5. This test determines whether the malfunction is in

IB16–BLU/ORG.

Diagnostic Aids:

An intermittent condition is likely to be caused by a short
to ground in the passenger pretensioner assembly circuit.
Inspect IB15–BLU/BLK and IB16–BLU/ORG carefully for
cutting or chafing.  If the wiring pigtail of the passenger
pretensioner assembly is damaged, the component must
be replaced.

RESTRAINT CONTROL SYSTEM

9J1–44

DTC 29 Passenger Pretensioner Loop Short To Ground 

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. Ignition switch “OFF.”
3. Connect scan tool data link connector.  follow directions as

given in the scan tool operator’s MANUAL.

4. Ignition switch “ON.”
5. Read passenger sense LO.

Is passenger sense LO less than 1.5 volts?

Go to Step 3

Go to Chart A

3

1. Ignition switch “OFF.”
2. Disconnect passenger pretensioner assembly yellow 2–pin

connector at the base of the passenger seat.

3. Leave driver pretensioner assembly connected.
4. Connect SRS driver / passenger load tool 5–8840–2421–0

and appropriate adapter to passenger pretensioner assembly
harness connector.

5. Ignition switch “ON.”

Is DTC 29 current?

Go to Step 4

Ignition switch

“OFF”

Replace

passenger

pretensioner

assembly 

Go to Step 6

4

1. Ignition switch “OFF”.
2. Disconnect SRS driver / passenger load tool
3. Measure resistance on SDM harness connector from terminal

“9” to terminal “6” (ground).

Does 5–8840–0285–0 display “OL” (Infinite)?

Go to Step 5

Replace SRS

harness or repair

chassis harness

Go to Step 6

5

Measure resistance on SDM harness connector from terminal
“10” to terminal “6” (ground).

Does 5–8840–0285–0 display “OL” (Infinite)?

Go to Chart A

Replace SRS

harness or repair

chassis harness

Go to Step 6

6

1. Reconnect all components and ensure all component are

properly mounted.

2. Clear diagnostic trouble codes.

Was this step finished?

Go to the “SRS

Diagnostic

system Check” 

Go to Step 6