GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Impala 🢒 Restraints 🢒 SIR 🢒 DTC B0018

Circuit Description

The inflatable restraint IP module deployment loop consists of a dual stage inflatable restraint IP module, the IP module stage 1 high circuit, and the IP module stage 1 low circuit. A shorting bar is used in the inflatable restraint IP module connector which shorts together the IP module stage 1 high and IP module stage 1 low circuits when the connector is disconnected. This will help prevent unwanted deployment of the IP module 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

The DTC will set if one of the following conditions occurs:

    • IP module stage 1 high circuit is more than 6 volts for 500 milliseconds during the deployment loop voltage out of range test.
    • IP module stage 1 high circuit is less than 2.4 volts and the IP module deployment loop resistance is less than 6 ohms for 500 milliseconds during the deployment loop resistance measurement test.

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 to ground or a short to voltage in the IP module stage 1 high or IP module stage 1 low circuits
    • The IP module connector
    • A malfunctioning IP module
    • The SDM connector
    • An internal SDM 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 intermittent.

    2.

  2. Tests to see if the malfunction is caused by the IP module.

    3.

  3. Tests to see if there is a short to ground or a short to voltage in the IP module stage 1 high or IP module stage 1 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. If DTC B0017 is also displayed, repair DTC B0017 first. Refer to DTC B0017 .
  2. Turn OFF the ignition.
  3. Disconnect the IP module connector. Refer to Inflatable Restraint Instrument Panel Module Replacement .
  4. Inspect the component and harness sides of the IP module connector for damage or corrosion that may cause the malfunction. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Does the IP module connector exhibit any signs of damage or corrosion?

Go to Step 3

Go to Step 4

3
  1. If the component side of the IP module connector is damaged, the IP module must be replaced.
  2. If the harness side of the IP module 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 IP module 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 B0018 is current?

Go to Step 5

Go to Diagnostic Aids

5

  1. Turn OFF the ignition.
  2. Disconnect the IP module connector.

    3. Important: When installing the J 38715-A SIR Driver/Passenger Load Tool for testing the dual stage IP module, the correct 4-way load tool adapter must be used. Failure to use the correct 4-way load tool adaptor will set additional codes during testing.

  3. Use the J 38715-80 adaptor to connect the J 38715-A SIR Driver/Passenger Load Tool PASSENGER INFLATOR and BASE OF COLUMN connectors to the harness side of the IP module 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 B0018 is current?

Go to Step 7

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Replace the IP module. Refer to Inflatable Restraint Instrument Panel 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 IP module stage 1 high and IP module stage 1 low circuits for a short to ground or a short to voltage. 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