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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Tahoe 4WD - RHD 🢒 Restraints 🢒 SIR 🢒 AIR BAG Warning Lamp Comes On Steady

Object Number: 477107 Size: MF
SIR Components
SIR Schematics
Handling ESD Sensitive Parts Notice
SIR Handling Caution

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 seven 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 two 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 Digital Multimeter with the correct terminal adapter from the J 35616-A Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Intermittents and Poor Connections in Restraints, 1999 C/K Service Manual. When a wire, connector or terminal repair is requested, use the J 38125-B Terminal Repair Kit. Refer to Wiring Repair in Restraints, 1999 C/K Service Manual.

Test Description

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

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

    2.

  2. This test checks for excessive IGNITION 1 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 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 checks 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 checks for a disconnected SDM.

    12.

  12. This test checks 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 in Restraints, 1999 C/K Service Manual

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, 1999 C/K Service Manual

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.

Are the repairs complete?

--

Go to SIR Diagnostic System Check in Restraints, 1999 C/K Service Manual

--

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 Infl Rst Sensing and Diagnostic Module Replacement in Restraints, 1999 C/K Service Manual.
  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 SDM Integrity Check in Restraints, 1999 C/K Service Manual

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 in Wiring Systems, 1999 C/K Service Manual.

Are the repairs complete?

--

Go to Step 34

--

9
  1. Install J 38715-96 within the SDM harness connector.
  2. Install the CPA.
  3. Disconnect the IP harness connector C232. Refer to SIR Components .
  4. Inspect the shorting bar within the IP harness side of connector C232.

Is the shorting bar damaged or corroded?

--

Go to Step 10

Go to Step 11

10

Replace the IP harness side of connector C232. Refer to Connector Repairs in Wiring Systems, 1999 C/K Service Manual.

Has the IP harness side of connector C232 been replaced?

--

Go to Step 11

--

11

Check for proper connection at terminal A1 and A2 on the IP harness side of connector C232.

Are the terminals damaged or corroded?

--

Go to Step 12

Go to Step 13

12

Replace the IP harness side of connector C232.

Refer to Connector Repairs in Wiring Systems, 1999 C/K Service Manual.

Has the IP harness side of connector been replaced?

--

Go to Step 13

--

13

Check for proper connection at terminals A1 and A2 on the harness side of connector C232.

Are the terminals damaged or corroded?

--

Go to Step 14

Go to Step 15

14

Replace the harness side of connector C232. Refer to Connector Repairs in Wiring Systems, 1999 C/K Service Manual.

Has the harness side of connector C232 been replaced?

--

Go to Step 33

--

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 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 18

Go to Step 17

17

Repair a short to ground condition in CKT 358.

Are the repairs complete?

--

Go to Step 34

--

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

Are the repairs complete?

--

Go to Step 34

--

19

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

Was a repair necessary?

--

Go to Step 34

Go to Step 20

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 26

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 25

Go to Step 22

22

  1. Disconnect the SDM. Refer to Infl Rst Sensing and Diagnostic Module Replacement in Restraints, 1999 C/K Service Manual.
  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 24

Go to Step 23

23
  1. Repair a short to ground condition in CKT 1139.
  2. Connect the SDM.
  3. Replace the Air Bag Fuse.

Are the repairs complete?

--

Go to Step 34

--

24
  1. Replace the SDM. Refer to Infl Rst Sensing and Diagnostic Module Replacement in Restraints, 1999 C/K Service Manual.
  2. Install the Air Bag Fuse.

Are the repairs complete?

--

Go to Step 34

--

25

Install the Air Bag Fuse.

Are the repairs complete?

--

Go to Step 34

--

26

Inspect the SDM harness connector.

Is the connector securely connected to the SDM?

--

Go to Step 28

Go to Step 27

27
  1. Properly connect the SDM harness connector.
  2. Install the CPA.

Are the repairs complete?

--

Go to Step 34

--

28
  1. Disconnect the inflatable restraint steering wheel and IP module yellow 2-way connectors located neat the base of the steering column.
  2. Disconnect the SDM. Refer to Infl Rst Sensing and Diagnostic Module Replacement in Restraints, 1999 C/K Service Manual.
  3. Check for proper connection to the SDM at terminal 10.

Is the SDM harness connector terminal damaged or corroded?

--

Go to Step 29

Go to Step 30

29

Replace the SDM harness connector. Refer to Connector Repairs in Wiring Systems, 1999 C/K Service Manual.

Are the repairs complete?

--

Go to Step 34

--

30

Inspect the SDM terminals for damage or corrosion.

Are any terminals damaged or corroded?

--

Go to Step 31

Go to Step 32

31

Replace the SDM. Refer to Infl Rst Sensing and Diagnostic Module Replacement in Restraints, 1999 C/K Service Manual.

Are the repairs complete?

--

Go to Step 27

--

32

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

Is either resistance reading within the specified values?

0-5 ohms

Go to SDM Integrity Check in Restraints, 1999 C/K Service Manual

Go to Step 33

33

Repair an open condition in CKT 1139.

Are the repairs complete?

--

Go to Step 34

--

34

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 in Restraints, 1999 C/K Service Manual

--