GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Lumina 🢒 Restraints 🢒 SIR 🢒 AIR BAG Warning Lamp Comes On Steady

Object Number: 212610 Size: SF
SIR Components new
SIR Schematics
SIR Caution
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The ignition switch supplies Ignition 1 voltage to the inflatable restraint Sensing and Diagnostic Module (SDM) at terminal 10 using Fuse 21. The ignition switch also supplies Ignition 1 voltage to the AIR BAG warning lamp using Fuse 39. The AIR BAG warning lamp is connected to the INFLATABLE RESTRAINT INDICATOR at terminal 7 of the SDM. When the ignition switch is first turned to RUN, the 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 turn 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 checks for sufficient IGNITION voltage applied to the SDM.

    2.

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

    3.

  3. This test checks 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 checks 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 checks for a short between CKT 358 and CKT 1751.

    8.

  8. An open Fuse 21 would cause the AIR BAG warning lamp to come on steady.

    9.

  9. This test checks whether a short to ground caused Fuse 21 to open.

    10.

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

    11.

  11. This test checks for a disconnected SDM.

    12.

  12. This test checks for an open in the IGNITION 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 a scan tool to the Data Link Connector (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 14

3

  1. Set the parking brake.
  2. Start the engine.
  3. Using the scan tool, read the SIR data list.

Is IGNITION more than the specified value?

17.1 V

Go to Starter and 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.

Are the repairs complete?

--

Go to SIR Diagnostic System Check

--

6

  1. Disconnect the inflatable restraint steering wheel and IP module yellow 2-way connectors at the base of the steering column and behind the IP compartment door.
  2. Disconnect the SDM harness connector.
  3. Install J 38715-96 SIR Shorting Bar Tool to 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 Integrity Check

7

  1. Turn the ignition switch to the OFF position.
  2. Remove J 38715-96 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

Are the repairs complete?

--

Go to Step 28

--

9

  1. Install J 38715-96 to the SDM harness connector.
  2. Install the CPA.
  3. Disconnect the instrument cluster. Refer to IP Cluster Replacement in Instrument Panel, Gages and Console.
  4. Measure the resistance from the SDM harness connector terminal 7 to ground.

Is the resistance reading less than the specified value?

OL

Go to Step 10

Go to Step 13

10

  1. Disconnect CKT 1751 from G251. Refer to SIR Components .
  2. Measure the resistance from the SDM harness connector terminal 7 to terminal 6.

Is the resistance reading less than the specified value?

OL

Go to Step 12

Go to Step 11

11

Repair a short-to-ground condition in CKT 358.

Are the repairs complete?

--

Go to Step 28

--

12
  1. Repair the short between CKT 358 and CKT 1751.
  2. Inspect CKT 1751 for any cutting or chaffing.

Are the repairs complete?

--

Go to Step 28

--

13

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

Are the repairs complete?

--

Go to Step 28

--

14

  1. Turn the ignition switch to the OFF position.
  2. Remove Fuse 21.
  3. Inspect Fuse 21.

Is Fuse 21 good?

--

Go to Step 20

Go to Step 15

15

  1. Replace Fuse 21.
  2. Turn the ignition switch to the RUN position for 10 seconds.
  3. Turn the ignition switch to the OFF position.
  4. Remove Fuse 21.
  5. Inspect Fuse 21.

Is Fuse 21 good?

--

Go to Step 19

Go to Step 16

16

  1. Disconnect the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Replace Fuse 21.
  3. Turn the ignition switch to the RUN position for 10 seconds.
  4. Turn the ignition switch to the OFF position.
  5. Remove Fuse 21.
  6. Inspect Fuse 21.

Is Fuse 21 good?

--

Go to Step 18

Go to Step 17

17
  1. Repair a short-to-ground condition in CKT 1139.
  2. Connect the SDM.
  3. Replace Fuse 21.

Are the repairs complete?

--

Go to Step 28

--

18
  1. Replace the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Install Fuse 21.

Are the repairs complete?

--

Go to Step 28

--

19

Install Fuse 21.

Are the repairs complete?

--

Go to Step 28

--

20

Inspect the SDM harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Is the connector secure?

--

Go to Step 22

Go to Step 21

21
  1. Properly connect the SDM harness connector.
  2. Install the CPA.

Are the repairs complete?

--

Go to Step 28

--

22
  1. Disconnect the inflatable restraint steering wheel and IP module yellow 2-way connectors at the base of the steering column and behind the IP compartment door.
  2. Disconnect the SDM.
  3. Check for proper connection to the SDM at terminal 10.

Is the SDM harness connector terminal damaged or corroded?

--

Go to Step 23

Go to Step 24

23

Replace the SDM harness connector. Refer to Wiring Repair .

Are the repairs complete?

--

Go to Step 28

--

24

Inspect the SDM terminals for damage or corrosion.

Are any terminals damaged or corroded?

--

Go to Step 25

Go to Step 26

25

Replace the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Are the repairs complete?

--

Go to Step 28

--

26

Measure the resistance from the SDM harness connector terminal 10 to each terminal of Fuse 21 fuseholder.

Is either resistance reading within the specified values?

0-5 ohms

Go to Integrity Check

Go to Step 27

27

Repair an open condition in CKT 1139.

Are the repairs complete?

--

Go to Step 28

--

28

Reconnect all the SIR system components, make sure all the components are properly mounted.

Have all the SIR components been reconnected and properly mounted?

--

Go to SIR Diagnostic System Check

--