GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2008 🢒 Vibe - FWD 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B1820, B1821, B1822, or B1823

Circuit Description

The inflatable restraint side impact module deployment loop consists of an inflatable restraint side impact module, the side impact module - high and side impact module - low circuits. A shorting bar is used in the inflatable restraint side impact module connector which will short together the side impact module - high and side impact module - low circuits when the connector is disconnected, this will help to prevent unwanted deployment of the inflator module during servicing. When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (SDM) performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B1820 Left Side Air Bag Deployment Loop Resistance Too Low
    • DTC B1821 Left Side Air Bag Deployment Loop Resistance Too High
    • DTC B1822 Left Side Air Bag Deployment Loop Short To Ground
    • DTC B1823 Left Side Air Bag Deployment Loop Short To Voltage

Conditions for Running the DTC

Ignition 1 voltage is within the normal operating voltage range.

Conditions for Setting the DTC

B1820

This DTC will set when the SDM detects a low resistance condition in the side impact module - LF deployment loop.

B1821

This DTC will set when the SDM detects a high resistance condition in the side impact module - LF deployment loop.

B1822

This DTC will set when the SDM detects a short to ground in the side impact module - LF deployment loop.

B1823

This DTC will set when the SDM detects a short to voltage in the side impact module - LF deployment loop.

Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator to flash.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

Diagnostic Aids

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.

The following are possible causes of the malfunction:

    • A short between the side impact module - high and the side impact module - low circuits
    • An open or high resistance in the side impact module - high or the side impact module - low circuits
    • A short to ground in the side impact module - high or the side impact module - low circuits
    • A short to voltage in the side impact module - high or the side impact module - low circuits
    • A malfunctioning inflatable restraint side impact module
    • An internal SDM malfunction

If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests to see if the malfunction is caused by the inflatable restraint side impact module.

    2.

  2. This step tests to see if the malfunction is caused by the inflatable restraint side impact module.

    3.

  3. If DTC B1820 is present, test for a short between the side impact module - left - high and the side impact module - left - low circuits.

    If DTC B1821 is present, test the side impact module - left - high and the side impact module - left - low circuits for an open or high resistance.

    If DTC B1822 is present, test the side impact module - left - high and the side impact module - left - low circuits for a short to ground.

    If DTC B1823 is present, test the side impact module - left - high and the side impact module - left - low circuits for a short to voltage.

Step

Action

Yes

No

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Is DTC B1820, B1821, B1822, or B1823 set as a current DTC?

Go to Step 3

Go to Diagnostic Aids

3
  1. Turn OFF the ignition.
  2. Disconnect the side impact module - LF connector.
  3. Inspect both the component and harness sides of the connector for damage or corrosion that may cause the malfunction. Refer to Testing for Intermittent Conditions and Poor Connections .

Does the connector exhibit any signs of damage or corrosion?

Go to Step 4

Go to Step 5

4
  1. If the component side of the side impact module connector is damaged, the side impact module must be replaced. Refer to Inflatable Restraint Side Impact Module Replacement - Left Side .
  2. If the harness side of the side impact module connector is damaged, replace the harness side of the connector. Refer to Connector Repairs .

Did you complete the replacement?

Go to Step 13

--

5

Is DTC B1821, B1822 or B1823 set as a current DTC?

Go to Step 7

Go to Step 6

6

Is DTC B1820 set as a current DTC?

Go to Step 8

--

7

  1. Connect a 3-amp fused jumper wire between the side impact module - high and the side impact module - low circuits on the harness side of the side impact module connector.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool in order to Clear the DTCs.
  4. With the scan tool, request the SIR DTC display.

Does the scan tool indicate that DTC B1821, B1822, or B1823 is current?

Go to Step 9

Go to Step 11

8

  1. Turn ON the ignition, with the engine OFF.
  2. Use the scan tool in order to Clear the DTCs.
  3. With the scan tool, request the SIR DTC display.

Does the scan tool indicate that DTC B1820 is current?

Go to Step 9

Go to Step 11

9
  1. Turn OFF the ignition.
  2. Disconnect the sensing and diagnostic module (SDM) connector.
  3. Inspect the SDM connector for damage or corrosion that may cause a malfunction in the side impact module - high and/or the side impact module - low circuits. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 10

10

  1. If DTC B1820 is present, test for a short between the side impact module - left - high and the side impact module - left - low circuits.
  2. If DTC B1821 is present, test the side impact module - left - high and the side impact module - left - low circuits for an open or high resistance.
  3. If DTC B1822 is present, test the side impact module - left - high and the side impact module - left - low circuits for a short to ground.
  4. If DTC B1823 is present, test the side impact module - left - high and the side impact module - left - low circuits for a short to voltage.
  5. For all of the above conditions, refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 12

11
  1. Turn OFF the ignition.
  2. Replace the side impact module - LF. Refer to Inflatable Restraint Side Impact Module Replacement - Left Side .

Did you complete the replacement?

Go to Step 13

--

12

Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Did you complete the replacement?

Go to Step 13

--

13
  1. Reconnect all SIR components.
  2. Verify that all components, connectors, and connector position assurances (CPAs) are properly mounted.
  3. Use the scan tool in order to Clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK