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

Circuit Description

The driver side deployment loop consists of an inflatable restraint side impact module-LF, the side impact module high-LF and side impact module-LF low circuits. A shorting bar is used in the 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 to prevent unwanted deployment of the inflator module during servicing. During a frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy the inflatable restraint side impact module-RF. The 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 in non-volatile memory.

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 warning 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

The following are possible causes of the malfunction:

    • A short between the side impact module-LF high and low circuits
    • A malfunctioning side impact module-LF
    • A malfunctioning side impact module-LF wiring harness
    • An internal SDM malfunction

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. If an intermittent malfunction 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 caused by the side impact module-LF or by the side impact module-LF wiring harness.

    2.

  2. Tests for 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 A 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 wiring harness connector. Refer to Inflatable Restraint Side Impact Module Wiring Harness Replacement .
  3. Inspect the side impact module wiring harness connector for damage or corrosion that may cause a short between high and low circuits. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Does the connector exhibit any signs of damage or corrosion?

Go to Step 3

Go to Step 4

3
  1. If the side impact module wiring harness connector is damaged, wiring harness must be replace. Refer to Inflatable Restraint Side Impact Module Wiring Harness Replacement .
  2. If the wiring harness side of side impact module wiring harness connector is damaged, replace the harness side of the connector. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

--

4
  1. Connect the J 38715-A SIR Driver/Passenger Load Tool to the wiring harness side of the side impact module-LF connector. Use PASSENGER INFLATOR connector.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool to request SIR DTCs displayed.

Does the scan tool indicate that this DTC 0040 is current?

Go to Step 8

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the J 38715-A .
  3. Reconnect the side impact module-LF wiring harness connector.
  4. Disconnect side impact module-LF connector. Refer to Driver and Passenger Seat Side Inflatable Restraint Module Replacement .
  5. Use the J 38715-30 adapter to connect the J 38715-A to the side impact module-LF connector. Use PASSENGER INFLATOR connector.
  6. Turn ON the ignition, with the engine OFF.
  7. Use the scan tool to request SIR DTCs displayed.

Does the scan tool indicate that this DTC 0040 is current?

Go to Step 6

Go to Step 7

6
  1. Turn OFF the ignition.
  2. Replace the side impact module-LF wiring harness. Refer to Inflatable Restraint Side Impact Module Wiring Harness Replacement .

Did you complete the replacement?

Go to Step 11

--

7
  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 11

--

8
  1. Turn OFF the ignition.
  2. Remove the J 38715-A .
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM) connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Inspect the SDM connector for damage or corrosion that may cause a short between the side impact module-LF high and the side impact module-LF low circuits. 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 11

Go to Step 9

9

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

Did you find and correct the condition?

Go to Step 11

Go to Step 10

10
  1. Turn OFF the ignition.
  2. Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Did you complete the replacement?

Go to Step 11

--

11
  1. Use the scan tool in order to Clear the DTCs.
  2. 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