GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Envoy - 4WD 🢒 Restraints 🢒 SIR 🢒 AIR BAG Warning Lamp Comes On Steady

Object Number: 389962 Size: MF
Cell 10: ILLUM, PARK LP Fuses
Cell 10: TURN, SIR and GAUGES Fuses
Cell 10: TURN, SIR and GAUGES Fuses
Cell 51: Power and Ground
SIR Components
Cell 47: IP Module Switch
SIR Handling Caution
Handling ESD Sensitive Parts Notice
SIR Schematic Icons
Cell 14: G203 and G204 (Pickup)
Handling ESD Sensitive Parts Notice
Cell 14: G203 and G204 (Pickup)

Circuit Description

When the ignition switch is first turned to the RUN position, the GAUGES Fuse applies battery voltage to the AIR BAG warning lamp that is connected to AIR BAG INDICATOR CONTROL, terminal 7. The SIR Fuse applies battery voltage to the IGNITION 1 input, terminal 10. The inflatable restraint sensing and diagnostic module (SDM) responds by flashing the AIR BAG warning lamp 7 times. If IGNITION 1 is outside of the normal operating voltage range (8.2 volts-17.1 volts), the AIR BAG warning lamp will come ON solid with no DTCs set.

Diagnostic Aids

In order to disable the shorting bar from terminal 6 to terminal 7 inside the inflatable restraint sensing and diagnostic module (SDM) harness connector, the following 2 conditions must be met:

    • The SDM harness connector must be properly connected to the SDM.
    • The connector position assurance (CPA) must be properly installed in the SDM harness connector.

When measurements are requested in this table, use the J 39200 DMM with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Testing for Electrical Intermittents in Wiring Systems. When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit and refer to Wiring Repairs in Wiring Systems.

Test Description

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

  1. This test inspects for sufficient IGNITION 1 voltage applied to the SDM.

    2.

  2. This test inspects for excessive IGNITION 1 voltage applied to the SDM.

    3.

  3. This test inspects for a properly installed CPA.

    4.

  4. This test determines if the SDM is turning on the AIR BAG warning lamp.

    5.

  5. This test inspects for a damaged shorting bar.

    6.

  6. This test determines whether the malfunction is a short to ground in CKT 358.

    7.

  7. This test determines whether an open SIR Fuse caused the AIR BAG warning lamp to come ON steady.

    8.

  8. This test inspects whether a short to ground caused the SIR Fuse to open.

    9.

  9. This test determines whether the short to ground is due to a short in the wiring or internal to the SDM.

    10.

  10. This test determines whether the short to ground is due to a short in the wiring or internal to the inflatable restraint IP module switch.

    11.

  11. This test inspects for a disconnected SDM.

    12.

  12. This test inspects for an open in the IGNITION 1 circuit.

AIR BAG Warning Lamp Comes On Steady

Step

Action

Value(s)

Yes

No

1

Was the SIR Diagnostic System Check performed?

--

Go to Step 2

Go to SIR Diagnostic System Check

2

  1. Turn the ignition switch to the OFF position.
  2. Connect the Scan Tool to the DLC.
  3. Turn the ignition switch to the RUN position.
  4. Request the SIR data list display.

Is IGNITION more than the specified value?

8.2 V

Go to Step 3

Go to Step 12

3

  1. Set the parking brake.
  2. Start the engine.
  3. Use the Scan Tool in order to read the SIR data list.

Is IGNITION more than the specified value?

17.1 V

Go to Charging System Check in Engine Electrical

Go to Step 4

4

  1. Turn the ignition switch to the OFF position.
  2. Inspect the inflatable restraint sensing and diagnostic module (SDM) harness connector CPA. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Is the CPA properly installed?

--

Go to Step 6

Go to Step 5

5

Properly install the CPA.

Is the repair complete?

--

Go to SIR Diagnostic System Check

--

6

  1. Disconnect the inflatable restraint steering wheel yellow 2-way connector at the base of the steering column and the IP module yellow 2-way connector located behind the glove box.
  2. Disconnect the SDM harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Install the J 38715-96 SIR Shorting Bar Tool within the SDM harness connector.
  4. Install the CPA.
  5. Turn the ignition switch to the RUN position.

Does the AIR BAG warning lamp come ON steady?

--

Go to Step 7

Go to Sensing and Diagnostic Module Integrity Check

7

  1. Turn the ignition switch to the OFF position.
  2. Remove the J 38715-96 SIR Shorting Bar Tool from the SDM harness connector.
  3. Inspect the shorting bar within the SDM harness connector.

Is the shorting bar damaged or corroded?

--

Go to Step 8

Go to Step 9

8

Replace the SDM harness connector. Refer to Wiring Repair .

Is the repair complete?

--

Go to Step 28

--

9

  1. Install the J 38715-96 SIR Shorting Bar Tool within the SDM harness connector.
  2. Install the CPA.
  3. Disconnect the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.
  4. Using the J 39200 Digital Multimeter (DMM) measure the resistance from the SDM harness connector terminal 7 to ground.

Is the resistance reading less then the specified value?

OL

Go to Step 10

Go to Step 11

10

Repair a short to ground condition in CKT 358.

Is the repair complete?

--

Go to Step 29

--

11

Service the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

Go to Step 29

 

12

  1. Turn the ignition switch to the OFF position.
  2. Remove the SIR Fuse.
  3. Inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 21

Go to Step 13

13

  1. Replace the SIR Fuse.
  2. Turn the ignition switch to the RUN position for 10 seconds.
  3. Turn the ignition switch to the OFF position.
  4. Remove the SIR Fuse.
  5. Inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 20

Go to Step 14

14

  1. Disconnect the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Replace the SIR Fuse.
  3. Turn the ignition switch to the RUN position for 10 seconds.
  4. Turn the ignition switch to the OFF position.
  5. Remove the SIR Fuse.
  6. Inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 19

Go to Step 15

15

Does this vehicle have an inflatable restraint IP module switch?

--

Go to Step 16

Go to Step 18

16

  1. Disconnect the inflatable restraint IP module switch. Refer to Inflatable Restraint Instrument Panel Module Disable Switch Replacement .
  2. Replace the SIR Fuse.
  3. Turn the ignition switch to the RUN position, wait 10 seconds, then turn the ignition switch to the OFF position.
  4. Remove and inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 17

Go to Step 18

17
  1. Replace the inflatable restraint IP module switch. Refer to Inflatable Restraint Instrument Panel Module Disable Switch Replacement .
  2. Install the SIR Fuse.

Has the inflatable restraint IP module switch been replaced and the SIR Fuse installed?

--

Go to Step 29

--

18
  1. Repair a short to ground condition in CKT 1139.
  2. Connect the SDM.
  3. Replace the SIR Fuse.

Is the repair complete?

--

Go to Step 29

--

19
  1. Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Install the SIR Fuse.

Is the repair complete?

--

Go to Step 29

--

20

Install the SIR Fuse.

Is the repair complete?

--

Go to Step 29

--

21

Inspect the SDM harness connector.

Is the connector securely connected to the SDM?

--

Go to Step 23

Go to Step 22

22
  1. Properly connect the SDM harness connector.
  2. Install the CPA.

Is the repair complete?

--

Go to Step 29

--

23
  1. Disconnect the inflatable restraint steering wheel yellow 2-way connector at the base of the steering column and the IP module yellow 2-way connector located behind the glove box.
  2. Disconnect the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Inspect for proper connection to the SDM at terminal 10.

Is the SDM harness connector terminal damaged or corroded?

--

Go to Step 24

Go to Step 25

24

Replace the SDM harness connector. Refer to Wiring Repair .

Is the repair complete?

--

Go to Step 29

--

25

Inspect the SDM terminals for damage or corrosion.

Are any terminals damaged or corroded?

--

Go to Step 26

Go to Step 27

26

Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Is the repair complete?

--

Go to Step 22

--

27

Measure the resistance from the SDM harness connector terminal 10 to each terminal of the SIR Fuse fuseholder.

Is either resistance reading within the specified values?

0-5 ohms

Go to Sensing and Diagnostic Module Integrity Check

Go to Step 29

28

Repair an open condition in CKT 1139.

Is the repair complete?

--

Go to Step 29

--

29
  1. Reconnect all of the SIR system components.
  2. Ensure that all of the components are properly mounted.

Have all of the SIR components been reconnected and properly mounted?

--

Go to SIR Diagnostic System Check

--