GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Envoy - 4WD 🢒 DTC 🢒 DTC B0090

Circuit Description

When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM monitors the voltage levels at the passenger frontal SIR enable and disable terminals of the SDM to determine the position of the inflatable restraint IP module switch. The SDM then 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.
    • Passenger frontal SIR enable circuit is not shorted to voltage.
    • Passenger frontal SIR disable circuit is not shorted to voltage.

Conditions for Setting the DTC
    • The voltage detected at passenger frontal SIR enable terminal and passenger frontal SIR disable terminal are less than 1.0 volt when the passenger AIR BAG ON lamp is commanded ON.
    • The voltage detected at passenger frontal SIR enable terminal and passenger frontal SIR disable terminal are greater than 4.0 volts when the passenger AIR BAG ON lamp is commanded OFF.
    • The voltage detected at passenger frontal SIR enable terminal and passenger frontal SIR disable terminal are greater than 1.0 volt when the passenger AIR BAG OFF lamp is commanded ON.

Action Taken When the DTC Sets
    • The inflatable restraint IP module switch is defaulted to a calibration state.
    • The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.

Conditions for Clearing the DTC
    • The inflatable restraint IP module switch AIR BAG lamp is OFF, and the voltage at passenger frontal SIR enable and passenger frontal SIR disable terminals are in opposite states for 500 milliseconds.
    • You issue a scan tool CLEAR CODES command.
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

When the SDM detects that no DTCs are present, the SDM commands the AIR BAG warning lamp OFF.

Diagnostic Aids

The following can cause an intermittent condition:

A short between the passenger frontal SIR enable and passenger frontal SIR disable circuits.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. Test determines if the passenger AIR BAG ON lamp illuminates when the inflatable restraint IP module switch is in the ON position.

    2.

  2. Tests for a poor connection at the inflatable restraint IP module switch harness connector.

    3.

  3. Test determines whether the malfunction is in the inflatable restraint IP module switch ground circuit.

    4.

  4. Test determines whether the malfunction is in the power feed circuit between the fuse block and the inflatable restraint IP module switch.

    5.

  5. Tests for proper contact or corrosion of the inflatable restraint sensing and diagnostic module (SDM) harness connector.

    6.

  6. Tests for an open or high resistance in the passenger SIR enable circuit.

    7.

  7. Tests for a short to ground in the passenger SIR enable circuit.

    8.

  8. Tests for a short to voltage in the passenger SIR disable circuit.

    9.

  9. Tests for a short between the passenger SIR enable and disable circuits.

    10.

  10. Tests for a short to voltage in the passenger SIR disable circuit.

    11.

  11. Tests for a short to voltage in the passenger SIR enable circuit.

    12.

  12. Tests for an open or high resistance in the passenger SIR disable circuit.

    13.

  13. Tests for a short to ground in the passenger SIR disable circuit.

Step

Action

Value(s)

Yes

No

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

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. Turn the inflatable restraint IP module switch to the ON position.
  3. Turn ON the ignition, with the engine OFF.

Does the passenger AIR BAG ON lamp illuminate in the IP module switch?

--

Go to Step 10

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Remove the inflatable restraint IP module switch from the instrument panel cluster (IPC). Refer to Inflatable Restraint Instrument Panel Module Disable Switch Replacement .
  3. Inspect the inflatable restraint IP module switch wiring harness connector for the following conditions:
    • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

Does the connector exhibit any signs of corrosion, terminal damage, or poor connections?

--

Go to Step 4

Go to Step 5

4

Repair or replace the inflatable restraint IP module switch harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the replacement?

--

Go to Step 33

--

5

Inspect the inflatable restraint IP module switch terminals for the following conditions:

    • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

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

--

Go to Step 32

Go to Step 6

6

  1. Disable the SIR system. Refer to Disabling the SIR System .
  2. UsingJ 39200 DMM measure the resistance of the ground circuit from the inflatable restraint IP module switch harness connector terminal to a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure greater than the specified value?

5 ohms

Go to Step 7

Go to Step 8

7

Locate and repair an open or high resistance in the inflatable restraint IP module switch ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

8

  1. Install the AIR BAG Fuse.
  2. Turn ON the ignition, with the engine OFF.
  3. Using theJ 39200 DMM measure the voltage between the inflatable restraint IP module switch harness connector terminal B and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure greater than the specified value?

1 V

Go to Step 10

Go to Step 9

9

Locate and repair an open or high resistance in the inflatable restraint IP module switch power feed circuit between the fuse block and the IP module switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

10
  1. Turn OFF the ignition.
  2. Install a scan tool.
  3. Turn the inflatable restraint IP module switch to the ON position.
  4. Turn ON the ignition, with the engine OFF.
  5. Use the scan tool to request the SIR data display.

Does the active switch show the specified state?

Enabled

Go to Step 20

Go to Step 11

11

  1. Turn OFF the ignition.
  2. Remove the AIR BAG Fuse.
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM) harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Inspect the SDM harness connector for the following conditions:
    5. • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

Does the connector exhibit any signs of corrosion, terminal damage, or poor connections?

--

Go to Step 21

Go to Step 12

12

UsingJ 39200 DMM measure the resistance of the passenger SIR enable circuit between the inflatable restraint IP module switch harness connector and the SDM harness connector.

Does the resistance measure greater than the specified value?

5 ohms

Go to Step 13

Go to Step 14

13

Locate and repair an open or high resistance in the passenger SIR enable circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

14

UsingJ 39200 DMM measure the resistance of the passenger SIR enable circuit from the inflatable restraint IP module harness connector to a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

OL

Go to Step 15

Go to Step 16

15

Locate and repair a short to ground in the passenger SIR enable circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

16

  1. Reconnect the inflatable restraint IP module switch harness connector. Refer to Inflatable Restraint Instrument Panel Module Disable Switch Replacement .
  2. Install the AIR BAG Fuse.
  3. Turn ON the ignition, with the engine OFF.
  4. Turn the inflatable restraint IP module switch to the OFF position.
  5. UsingJ 39200 DMM measure the voltage of the passenger SIR disable circuit between the inflatable restraint IP module switch harness connector and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure greater than the specified value?

1 V

Go to Step 17

Go to Step 18

17

Locate and repair a short to voltage in the passenger SIR disable circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

18

  1. Turn OFF the ignition.
  2. UsingJ 39200 DMM measure the resistance between the passenger SIR enable and the passenger SIR disable circuits at the inflatable restraint IP module harness connector. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

OL

Go to Step 19

Go to Step 32

19

Locate and repair a short between the passenger SIR enable and passenger SIR disable circuits. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

20
  1. Turn OFF the ignition.
  2. Disable the SIR system. Refer to Disabling the SIR System .
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM) harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Inspect the SDM harness connector for the following conditions:
    5. • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

Does the connector exhibit any signs of corrosion, terminal damage, or poor connections?

--

Go to Step 21

Go to Step 22

21

Repair or replace the inflatable restraint sensing and diagnostic module (SDM) harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

22
  1. Turn OFF the ignition.
  2. Remove the inflatable restraint IP module switch from the instrument panel cluster (IPC). Refer to Inflatable Restraint Instrument Panel Module Disable Switch Replacement .
  3. Inspect the inflatable restraint IP module switch wiring harness connector for the following conditions:
    4. • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

Does the connector exhibit any signs of corrosion, terminal damage, or poor connections?

--

Go to Step 23

Go to Step 24

23

Repair or replace the inflatable restraint IP module switch harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

24

  1. Reconnect the inflatable restraint sensing and diagnostic module (SDM) harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Turn ON the ignition, with the engine OFF.
  3. UsingJ 39200 DMM measure the voltage of the passenger SIR disable circuit between the inflatable restraint IP module switch harness connector and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure greater than the specified value?

1 V

Go to Step 25

Go to Step 26

25

Locate and repair a short to voltage in the passenger SIR disable circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

26

UsingJ 39200 DMM measure the voltage of the passenger SIR enable circuit between the inflatable restraint IP module switch harness connector and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure greater than the specified value?

1 V

Go to Step 27

Go to Step 28

27

Locate and repair a short to voltage in the passenger SIR enable circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

28

  1. Turn OFF the ignition.
  2. UsingJ 39200 DMM measure the resistance of the passenger SIR disable circuit between the inflatable restraint IP module harness connector and the inflatable restraint sensing and diagnostic module (SDM) harness connector. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure greater than the specified value?

5 ohms

Go to Step 29

Go to Step 30

29

Locate and repair an open or high resistance in the passenger SIR disable circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

30

UsingJ 39200 DMM measure the resistance between the passenger SIR disable circuit and the ground circuit at the inflatable restraint IP module switch harness connector. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

OL

Go to Step 31

Go to Step 32

31

Locate and repair a short to ground in the passenger SIR disable circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 33

--

32

Replace the inflatable restraint IP module switch. Refer to Inflatable Restraint Instrument Panel Module Disable Switch Replacement .

Did you complete the repair?

--

Go to Step 33

--

33
  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