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Makes 🢒 Cadillac 🢒 2008 🢒 SLS 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 DTC B0021

Circuit Description

Driver side deployment loop is composed of the following parts:

    • Airbag side impact module - right front
    • Airbag side impact module harness
    • Side Impact Module - right front - high control
    • Side Impact Module - right front- low Control

There are 2 shorting bars used within the right front side impact module connector. When the connector disconnects, the shorting bar shorts the right front side impact module high and low control circuits. This helps to prevent the inflation module to deploy accidentally during servicing. During a side or frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop. The right front side impact module will deploy. The SDM performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage. Any DTC detected will be stored in the memory.

DTC Descriptors

The diagnostic procedure supports the following DTC:

DTC B0021 Right Front Side Airbag Deployment Loop

The vehicle has DTCs including the DTC symptoms. Refer to DTC Symptom Description for DTC information.

DTC Symptom

DTC Symptom Descriptor

01

Short to battery

02

Short to ground

04

Open circuit

0D

Resistance above threshold

0E

Resistance below threshold

Conditions for Running the DTC

Ignition voltage is within normal operating range.

Conditions for Setting the DTC

B0021 01

The right front side impact module high and/or low circuit is short to voltage for 120 milliseconds.

B0021 02

The right front side impact module high and/or low circuit is short to ground for 120 milliseconds.

B0021 04

The right front side impact module high and/or low circuit is open for 120 milliseconds.

B0021 0D

The right front side impact module deployment loop resistance is more than 3.9 ohms for 120 milliseconds.

B0021 0E

The right front side impact module deployment loop resistance is less than 1.1 ohms for 120 milliseconds.

Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON via GMLAN serial data communications.

Conditions for Clearing the MIL/DTC
    • When conditions for the DTC to set no longer exist, use CLEAR DTC function of the scan tool to clear the DTC.
    • After 255 consecutive warm-up cycles without failure, the DTC will be cleared.

Diagnostic Aids

The following may be the possible causes for the fault:

    • The right front side impact module high and/or low circuit is short circuited.
    • The right front side impact module high and/or low circuit has high resistance.
    • The right front side impact module high and/or low circuit is short to ground or voltage.
    • Side impact module connector - right front
    • The SDM harness connector
    • Side impact module harness fault
    • Right front side impact module fault
    • The SDM module fault

Thoroughly inspect the wiring and connectors. Failure to do so may result in error of diagnosis and the trouble may occur again even when you replace the parts. If there is intermittent conditions, refer to Testing for Intermittent Conditions and Poor Connections .

Test Description

The following numbers are corresponding to the steps in the diagnostic table.

  1. Test if the fault is caused by right front side impact module or right front side impact module coil.

    2.

  2. Test to verify the set DTCs. If DTC B0021 01 is set, test if the right front side impact module high or low control is short to battery voltage. If DTC B0021 02 is set, test if the right front side impact module high or low control is short to ground. If DTC B0021 04, 0D, 0E is set, test if the right front side impact module high or low control is open or high or low resistance.

Step

Action

Yes

No

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

1

Have you conducted Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn the ignition switch to OFF position.
  2. Disconnect the right front side impact module coil inline connector. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .
  3. Check the right front side impact module coil inline connector to see if there is damage or corrosion that may result in the fault. Refer to Testing for Intermittent Conditions and Poor Connections .

Is there damage or corrosion in the connectors?

Go to Step 3

Go to Step 4

3
  1. If the right front side impact module coil inline connector is damaged, replace the right front side impact module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .
  2. If the right front side impact module coil connector harness is damaged, replace the harness. Refer to Connector Repairs .

Is the trouble corrected?

Go to Step 11

--

4
  1. Use J 38715-80 adaptor, connect J 38715-A Airbag Driver/Passenger Load Special Tool to the right front side impact module coil connector harness. Use steering column base and passenger inflator connector.
  2. Engine off, ignition on.

    3. Important: J-45289 CANdi Module must be used together with the scan tool.

  3. Use the scan tool in order to display the SIR DTCs.

Does the scan tool display DTC B0021?

Go to Step 6

Go to Step 5

5

  1. Turn the ignition switch to OFF position.
  2. Disconnect and remove J 38715-A and the adaptor.
  3. Connect the right front side impact module coil inline connector.
  4. Remove the right front side impact module. Refer to Driver or Passenger Seat Side Inflatable Restraint Module Replacement .
  5. Use J 38715-120 Adaptor to connect the J 38715-A to the top of the right front side impact module coil connector above the steering column. Use steering column and passenger inflator connector.
  6. Engine OFF, ignition on.
  7. Use the scan tool in order to display the SIR DTCs.

Does the scan tool display DTC B0021?

Go to Step 9

Go to Step 8

6
  1. Turn the ignition switch to OFF position.
  2. Disconnect and remove J 38715-A and the adaptor.
  3. Disconnect the SIR system sensing and diagnostic module (SDM) connector. Refer to Control Module References for replacement, setup, and programming.
  4. Check if there is damage or corrosion to the SDM connector, which may result in trouble in right front side impact module stage 1 or stage 2 loop high and/or low control circuits. Refer to Testing for Intermittent Conditions and Poor Connections .

Did you find and correct the condition?

Go to Step 11

Go to Step 7

7

  1. If DTC B0021 01 is set, test if the right front side impact module - stage 1 and stage 2 - high or low control is short to battery voltage.
  2. If DTC B0021 02 is set, test if the right front side impact module - stage 1 and stage 2 - high or low control is short to ground.
  3. If DTC B0021 04, 0D, 0E is set, test if the right front side impact module - stage 1 and stage 2 - high or low control is open or high or low in resistance. Refer to Circuit Testing and Wiring Repairs for all the above situations.

Do you find and correct the condition?

Go to Step 11

Go to Step 10

8
  1. Turn the ignition switch to OFF position.
  2. Replace the right front side impact module. Refer to Driver or Passenger Seat Side Inflatable Restraint Module Replacement .

Have you finished the replacement?

Go to Step 11

--

9
  1. Turn the ignition switch to OFF position.
  2. Replace the right front side impact coil. Refer to Driver or Passenger Seat Side Inflatable Restraint Module Replacement .

Have you finished the replacement?

Go to Step 11

--

10
  1. Turn the ignition switch to OFF position.
  2. Replace the SDM module. Refer to Control Module References for replacement, setup, and programming.

Have you finished the replacement?

Go to Step 11

--

11
  1. Connect all SIR components.
  2. Engine off, ignition on.
  3. Clear away all DTCs with scan tool.
  4. Operate the vehicle under conditions when DTC runs as specified in supporting documents.

Does the DTC set again?

Go to Step 2

System is OK