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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Pickup - 4WD 🢒 Restraints 🢒 SIR 🢒 AIR BAG Warning Lamp Comes On Steady

Object Number: 389891 Size: MF
SIR Components
SIR System Component Description and Definitions
General Service Instructions
Handling ESD Sensitive Parts Notice

Circuit Description

When the ignition switch is first turned to RUN, the GAUGES Fuse applies battery voltage to the AIR BAG warning lamp that is connected to Air Bag Indicator Control, terminal 7. The AIR BAG 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 inspects for a short between CKTs 358 and 1751.

    8.

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

    9.

  9. This test inspects whether a short to ground caused the AIR BAG Fuse 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 determines whether the short to ground is due to a short in the wiring or internal to the inflatable restraint IP module switch.

    12.

  12. This test inspects for a disconnected SDM.

    13.

  13. 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 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 20

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 Charging System Check in Engine Electrical

Go to Step 4

4
  1. Turn the ignition switch to the OFF position.
  2. Inspect the SDM harness connector CPA.

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 and IP module yellow 2-way connectors located near the base of the steering column.
  2. Disconnect the SDM harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Install 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 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 Connector Repairs

Is the repair complete?

--

Go to Step 36

--

9
  1. Install J 38715-96 within the SDM harness connector.
  2. Install the CPA.
  3. Disconnect the IP harness connector C 232. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Inspect the shorting bar within the IP harness side of connector C 232.

Is the shorting bar damaged or corroded?

--

Go to Step 10

Go to Step 11

10

Replace the IP harness side of connector C 232. Refer to Connector Repairs .

Has the IP harness side of connector C 232 been replaced?

--

Go to Step 11

--

11

Inspect for proper connection at terminals A1 and A2 on the IP harness side of connector C 232.

Are the terminals damaged or corroded?

--

Go to Step 12

Go to Step 13

12

Replace the IP harness side of connector C 232. Refer to Connector Repairs in Wiring Systems.

Has the IP harness side of connector been replaced?

--

Go to Step 13

--

13

Inspect for proper connection at terminals A1 and A2 on the harness side of connector C 232.

Are the terminals damaged or corroded?

--

Go to Step 14

Go to Step 15

14

Replace the harness side of connector C 232. Refer to Connector Repairs in Wiring Systems.

Has the harness side of connector C 232 been replaced?

--

Go to Step 36

--

15

  1. Disconnect the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.
  2. 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 16

Go to Step 19

16

  1. Disconnect CKT 1751 from ground. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  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 18

Go to Step 17

17

Repair a short to ground condition in CKT 358.

Is the repair complete?

--

Go to Step 37

--

18
  1. Repair the short between CKTs 358 and 1751.
  2. Inspect CKT 1751 for any cutting or chaffing.

Is the repair complete?

--

Go to Step 37

--

19

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

Is the repair complete?

--

Go to Step 37

--

20

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

Is the AIR BAG Fuse good?

--

Go to Step 29

Go to Step 21

21

  1. Replace the AIR BAG 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 AIR BAG Fuse.
  5. Inspect the AIR BAG Fuse.

Is the AIR BAG Fuse good?

--

Go to Step 28

Go to Step 22

22

  1. Disconnect the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Replace the AIR BAG 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 AIR BAG Fuse.
  6. Inspect the AIR BAG Fuse.

Is the AIR BAG Fuse good?

--

Go to Step 27

Go to Step 23

23

Does this vehicle have an inflatable restraint IP module switch?

--

Go to Step 24

Go to Step 26

24

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

Is the AIR BAG Fuse good?

--

Go to Step 25

Go to Step 26

25
  1. Replace the inflatable restraint IP module switch. Refer to Inflatable Restraint Instrument Panel Module Disable Switch Replacement .
  2. Install the AIR BAG Fuse.

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

--

Go to Step 37

--

26
  1. Repair a short to ground condition in CKT 1139.
  2. Connect the SDM.
  3. Replace the AIR BAG Fuse.

Is the repair complete?

--

Go to Step 37

--

27
  1. Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Install the AIR BAG Fuse.

Is the repair complete?

--

Go to Step 37

--

28

Install the AIR BAG Fuse.

Is the repair complete?

--

Go to Step 37

--

29

Inspect the SDM harness connector.

Is the connector securely connected to the SDM?

--

Go to Step 31

Go to Step 30

30
  1. Properly connect the SDM harness connector.
  2. Install the CPA.

Is the repair complete?

--

Go to Step 37

--

31
  1. Disconnect the inflatable restraint steering wheel and IP module yellow 2-way connectors located near the base of the steering column.
  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 32

Go to Step 33

32

Replace the SDM harness connector. Refer to Wiring Repair .

Is the repair complete?

--

Go to Step 37

--

33

Inspect the SDM terminals for damage or corrosion.

Are any terminals damaged or corroded?

--

Go to Step 34

Go to Step 35

34

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

Is the repair complete?

--

Go to Step 30

--

35

Measure the resistance from the SDM harness connector terminal 10 to each terminal of the AIR BAG Fuse fuse holder.

Is either resistance reading within the specified values?

0-5 ohms

Go to Sensing and Diagnostic Module Integrity Check

Go to Step 36

36

Repair an open condition in CKT 1139.

Is the repair complete?

--

Go to Step 37

--

37
  1. Reconnect all the SIR system components.
  2. Ensure that all of the components are properly mounted.

Have all the SIR components been reconnected and properly mounted?

--

Go to SIR Diagnostic System Check

--