GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Impala 🢒 Restraints 🢒 SIR 🢒 DTC B0040 LF/Driver Side Deployment Loop Resistance Low

Object Number: 490881 Size: SF
SIR Components
Power, Ground, Side Impact Sensor, and Frontal Air Bags
Handling ESD Sensitive Parts Notice
SIR Caution

Circuit Description

When you first turn ON the ignition, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Then the SDM performs the following continuous diagnostic tests on the deployment loops:

    • Deployment loop voltage out of range test
    • Deployment loop resistance measurement test

If the voltage out of range test detects a short to voltage condition, the resistance measurement test for that deployment loop will not be performed.

Conditions for Running the DTC
    • Ignition 1 voltage is within the normal operating voltage range.
    • Driver side deployment loop is not open.
    • Driver side deployment loop is not shorted to voltage.
    • Driver side deployment loop is not shorted to ground.

Conditions for Setting the DTC

Driver side deployment loop resistance is less than 1.3 ohms for 300 milliseconds.

Action Taken When the DTC Sets

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

Conditions for Clearing the DTC
    • You can issue a CLEAR CODES command
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred

Diagnostic Aids

The following can cause an intermittent condition:

    • A short between the driver side high and the driver side low circuits.
    • A malfunctioning shorting bar on the inflatable restraint side impact module - LH yellow 2-way connector.
    • Refer to cell-id="62112">Testing for Intermittent and Poor Connections> in Wiring Systems.

Test Description

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

  1. This step checks the inflatable restraint side impact module - LH yellow 2-way connector.

    2.

  2. This step checks to see if there is a malfunctioning inflatable restraint side impact module - LH.

    3.

  3. This step determines if there is a short between the driver side high and the driver side low or if there is a malfunctioning SDM.

Step

Action

Value(s)

Yes

No

1

Did you perform A Diagnostic System Check - SIR?

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Go to Step 2

Go to cell-id="57882">A Diagnostic System Check - SIR>

2

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint side impact module - LH yellow 2-way connector. Refer to Driver and Passenger Seat Side Inflatable Restraint Module Replacement .
  3. Inspect the component and harness sides of the inflatable restraint side impact module - LH yellow 2-way connector for the following conditions:
    4. • Corrosion
    • Damaged terminals
    • Poor connections/terminal tension
  4. Refer to cell-id="62112">Testing for Intermittent and Poor Connections> in Wiring Systems.

Does either the component or harness side of the inflatable restraint side impact module - LH yellow 2-way connector exhibit any signs of corrosion, terminal damage, or poor connections?

--

Go to Step 3

Go to Step 4

3
  1. If the component side of the inflatable restraint side impact module - LH yellow 2-way connector is damaged, the inflatable restraint side impact module - LH must be replaced.
  2. If the harness side of the inflatable restraint side impact module - LH yellow 2-way connector is damaged, replace the harness side of the connector. Refer to cell-id="61973">Connector Repairs> in Wiring systems.

Did you complete the repair?

--

Go to Step 10

--

4
  1. Reconnect the inflatable restraint side impact module - LH yellow 2-way connector.
  2. Verify that the connector position assurance (CPA) is properly installed.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool to request the SIR DTC display.

Does the scan tool indicate that this DTC is current?

--

Go to Step 5

Go to Diagnostic Aids

5

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint side impact module - LH yellow 2-way connector.
  3. Connect the J 38715-A SIR Driver/Passenger Load Tool PASSENGER INFLATOR connector to the harness side of the inflatable restraint side impact module - LH yellow 2-way connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Use the scan tool to request the SIR DTC display.

Does the scan tool indicate that this DTC is current?

--

Go to Step 7

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Replace the inflatable restraint driver seat module. Refer to cell-id="57801">Inflatable Restraint Side Impact Module Replacement - Front> .

Did you complete the replacement?

--

Go to Step 10

--

7

  1. Turn OFF the ignition.
  2. Remove the J 38715-A .
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM). Refer to cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> or cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> .
  4. Use the J 39200 Digital Multimeter (DMM) to measure the resistance between the driver side high and the driver side low circuits.

Does the resistance measure less than the specified value?

OL

Go to Step 8

Go to Step 9

8

Locate and repair a short between the driver side high and the driver side low circuits. Refer to cell-id="62194">Circuit Testing> and cell-id="61965">Wiring Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 10

--

9

Replace the SDM. Refer to cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> or cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> .

Did you complete the replacement?

--

Go to Step 10

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10
  1. Reconnect all SIR components.
  2. Verify that all components and connectors are properly mounted.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool in order to clear the DTCs.

Did you complete the action?

--

Go to cell-id="57882">A Diagnostic System Check - SIR>

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