Isuzu Rodeo UE. Manual - part 647

9J1–25

RESTRAINT CONTROL SYSTEM

DTC 21  Driver Deployment Loop Resistance High

D09RW002

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.
The SDM then proceeds with the “Resistance
Measurement Test” “Driver Bag Low” terminal “4” is
grounded through a current sink and the driver current
source connected to “Driver Bag High” terminal “3” allows
a known amount of current to flow.  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 CKTs IB05–YEL and IB06–YEL/BLK, and
connector terminal contact.

DTC Will Set When:

The combined resistance of the driver air bag assembly,
SRS Coil assembly, harness wiring CKTs IB05–YEL and
IB06–YEL/BLK, and connector terminal contact is above
a specified value.  This test run once each ignition cycle
during the “Resistance Measurement Test” when:
No “higher priority faults” are detected during

“Turn–ON”

“Ignition 1” voltage is in the specified value.

Action Taken:

SDM turns “ON” the “AIR BAG” warning lamp and sets
DTC 21.

DTC Will Clear When:

The ignition switch is turned “OFF”.

RESTRAINT CONTROL SYSTEM

9J1–26

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

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

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

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 SRS coil assembly or the driver air bag
assembly.

Diagnostic Aids:

An intermittent condition is likely to be caused by a poor
connection at terminals “1” and “2” of the SRS coil 2–pin
connector at the base of the steering column, terminal “1”
and “2” of the driver air bag assembly 2–pin connector at
the top of the steering column, SDM terminals “3” and “4”
or a poor wire to terminal connection in CKT IB05–YEL or
IB06–YEL/BLK.  The test for this diagnostic trouble code
is only run while the “AIR BAG” warning lamp is
performing the bulb check, unless DTC 17 or DTC 26 is
detected.  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.

9J1–27

RESTRAINT CONTROL SYSTEM

DTC 21 Driver Deployment Loop Resistance High 

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 J–39200

DVM with correct terminal adapter from J–35616–A.

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

deployment loop resistance.

Is driver deployment loop resistance more than 4.4 ohms?

Go to Step 3

Go to Chart A.

3

1. Ignition switch “OFF.”
2. Disconnect driver air bag assembly yellow 2–pin connector

located at base of steering column is seated properly.

Is the 2–pin connector connected properly?

Go to Step 4

Seat SRS coil

assembly 2–pin

connector

properly.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 21 current?

Go to Step 5

Ignition switch

“OFF.”

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 J–41433 and

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

4. Ignition switch “ON.”

Is DTC 21 current?

Go to Step 6

Go to Step 7

6

1. Ignition switch “OFF.”
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 CKTs IB05–YEL/IB06–GRN and 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.”

Disconnect SRS driver / passenger load tool from SRS coil
assembly harness connector.
Connect SRS driver / passenger load tool J–41433 on the top
of steering column.
Reconnect SRS coil assembly harness connector as the base
of steering column.
Ignition switch “ON.”

Is DTC 21 current?

Ignition switch

“OFF.”

Replace SRS

COIL

ASSEMBLY.

Refer to in this
section 9J–24.

Go to Step 8

Ignition switch

“OFF.”

Replace driver air

bag assembly.

Go to Step 8

8

Reconnect all components, ensure all component are properly
mounted.

Clear diagnostic trouble codes.

Was this step finished?

Repeat the “SRS

Diagnostic

System Check.” 

Go to Step 8.

RESTRAINT CONTROL SYSTEM

9J1–28

DTC 22  Driver Deployment Loop Resistance Low

D09RW002

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.The
SDM then proceeds with the “Resistance Measurement
Test” “Driver Bag Low” terminal “4” is grounded through a
current sink and the driver current source connected to
“Driver Bag High” terminal “3” allows a known amount of
current to flow.  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 CKTs
IB05–YEL and IB06–YEL/BLK and connector terminal
contact.

DTC Will Set When:

The combined resistance of the driver air bag assembly,
SRS coil assembly, harness wiring CKTs IB05–YEL and
IB06–YEL/BLK and connector terminal contact is above a
specified value.  This test is 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:

SDM turns “ON” the “AIR BAG” warning lamp and sets
DTC 22.

DTC Will Clear When:

The ignition switch is turned “OFF.”