GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Impala 🢒 Restraints 🢒 SIR 🢒 DTC B0040

Circuit Description

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

Conditions for Running the DTC

Ignition 1 voltage is within the normal operating voltage range.

Conditions for Setting the DTC

Side impact module - LF deployment loop resistance is less than 1.3 ohms for 500 milliseconds.

Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON via Class 2 serial data.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

Diagnostic Aids

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in 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 - LF high and side impact module - LF low circuits
    • The side impact module - LF connector
    • A malfunctioning side impact module - LF
    • The SDM connector
    • An internal SDM malfunction

If an intermittent condition exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests to see if the malfunction is intermittent.

    2.

  2. Tests to see if the malfunction is caused by the side impact module - LF.

    3.

  3. Tests to see if there is a short between the side impact module - LF high and side impact module - LF low circuits.

Step

Action

Yes

No

Schematic Reference: SIR Schematics

1

Did you perform the Diagnostic System Check - SIR?

Go to Step 2

Go to Diagnostic System Check - SIR

2
  1. Turn OFF the ignition.
  2. Disconnect the side impact module - LF connector. Refer to Driver and Passenger Seat Side Inflatable Restraint Module Replacement .
  3. Inspect the component and harness sides of the side impact module - LF connector for damage or corrosion that may cause the malfunction. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Does the side impact module - LF connector exhibit any signs of damage or corrosion?

Go to Step 3

Go to Step 4

3
  1. If the component side of the side impact module - LF connector is damaged, the side impact module - LF must be replaced.
  2. If the harness side of the side impact module - LF connector is damaged, replace the harness side of the connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 10

--

4

  1. Reconnect the side impact module - LF connector.
  2. Verify that the connector position assurance (CPA) is properly installed.
  3. Install a scan tool.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the SIR DTC display.

Does the scan tool indicate that DTC B0040 is current?

Go to Step 5

Go to Diagnostic Aids

5

  1. Turn OFF the ignition.
  2. Disconnect the side impact module - LF connector.
  3. Connect the J 38715-A SIR Driver/Passenger Load Tool PASSENGER INFLATOR connector to the harness side of the side impact module - LF connector.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the SIR DTC display.

Does the scan tool indicate that DTC B0040 is current?

Go to Step 7

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Replace the side impact module - LF. Refer to Driver and Passenger Seat Side Inflatable Restraint Module Replacement .

Did you complete the replacement?

Go to Step 10

--

7
  1. Turn OFF the ignition.
  2. Remove the J 38715-A .
  3. Disconnect the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Inspect the SDM connector for damage or corrosion that may cause the malfunction. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

8

Test the side impact module - LF high and side impact module - low circuits for a short between the two circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

9

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

Did you complete the replacement?

Go to Step 10

--

10
  1. Reconnect all SIR components.
  2. Use the scan tool in order to clear the DTCs.
  3. 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