GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Envoy - 4WD 🢒 DTC 🢒 DTC B0018

Circuit Description

The inflatable restraint IP module deployment loop consists of an inflatable restraint IP module, the IP module high, and IP module low circuits. A shorting bar is used on the inflatable restraint IP module connector which will short together the IP module high and IP 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.

Conditions for Running the DTC

Ignition 1 voltage is within the normal operating voltage range.

Conditions for Setting the DTC
    • The SDM detects the voltage at IP module high is greater than 6 volts for 500 milliseconds.
    • The SDM detects the voltage at IP module high is less than 2.4 volts and IP module high to IP module low resistance is less than 6 ohms for 500 milliseconds.

Action Taken When the DTC Sets
    • The SDM disables the passenger frontal deployment loop resistance test.
    • The SDM commands ON the AIR BAG indicator via Class 2 serial data.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists.
    • You issue a scan tool CLEAR DTCs 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 IP module high and IP module low circuits.
    • A malfunctioning shorting bar on the IP module connector.

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. This step inspects the IP module in-line connector.

    2.

  2. Tests for a malfunctioning IP module.

    3.

  3. Tests for a short to ground or voltage in the IP module low deployment circuit.

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 inflatable restraint IP module in-line connector.
  3. Inspect both halves of the connector for the following conditions:
    4. • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

Do the connectors exhibit any signs of corrosion, terminal damage, or poor connections?

Go to Step 3

Go to Step 4

3
  1. Replace the wiring harness side of the in-line connector. Refer to Connector Repairs in Wiring Systems.
  2. If the IP module harness connector exhibits any of the above conditions, the module must be replaced. Refer to Inflatable Restraint Instrument Panel Module Replacement .

Did you complete the replacement?

Go to Step 10

--

4
  1. Reconnect the IP module in-line 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 DTC B0018 is current?

Go to Step 5

Go to Diagnostic Aids

5

  1. Turn OFF the ignition.
  2. Disconnect the IP module in-line connector.
  3. Use the J 38715-100 adaptor to connect the J 38715-A SIR Load Tool to the wiring harness side of the in-line 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 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 SIR Load Tool and adaptor.
  3. Disconnect the SDM connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Inspect the SDM connector for corrosion or damage at the IP module high and IP module low deployment 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 10

Go to Step 8

8

Test the IP module high and IP module 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
  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 10

--

10
  1. Reconnect all SIR system components.
  2. Verify that all components, connectors and 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