GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Lumina 🢒 Restraints 🢒 SIR 🢒 AIR BAG Warning Lamp Comes On Steady

Object Number: 590606 Size: SF
SIR Component Views
Power, Ground, IP MIL, SDM, IP Module, Steering Wheel Coil, STeEring Wheel Module, Seat Belt Switch and Seat Belt/Ignition Key/Lamps Alarm
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
SIR Handling Caution

Circuit Description

The ignition switch supplies IGNITION 1 voltage to the inflatable restraint sensing and diagnostic module (SDM) 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 the SDM. When the ignition switch is first turned to RUN, the 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 DTC's set.

Diagnostic Aids

In order to disable the shorting bar from the inflatable restraint indicator circuit and the ground circuit inside the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector, the following two conditions must be met:

    • The SDM wiring harness connector must be properly connected to the SDM.
    • The connector position assurance (CPA) must be properly installed in the SDM wiring 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 step checks to see if sufficient IGNITION voltage is applied to the SDM.

    2.

  2. This step checks to see if excessive IGNITION voltage is applied to the SDM.

    3.

  3. This step checks to see if the connector position assurance (CPA) is properly installed.

    4.

  4. This step determines if the SDM is turning on the AIR BAG warning lamp or if there is a malfunctioning SDM.

    5.

  5. This step checks to see if the shorting bar is damaged.

    6.

  6. This step checks to see if there is a short to ground in CKT 358.

    7.

  7. This step determines if there is a short between the inflatable restraint indicator circuit and the ground circuit or if there is a short to ground in the inflatable restraint indicator circuit.

    8.

  8. This step checks to see if Fuse 21 is OK. An open Fuse 21 would cause the AIR BAG warning lamp to come on steady.

    9.

  9. This step checks to see if a short to ground caused Fuse 21 to open.

    10.

  10. This step checks to see if there is a short to ground in the ignition positive voltage circuit.

    11.

  11. This step checks to see if the SDM wiring harness connector properly secures to the SDM.

    12.

  12. This step checks to see if there is an open in the ignition positive voltage circuit.

    13.

  13. This step determines if there is an open or a high resistance in the B+ feed circuit to the input side of Fuse 21 or if there is a malfunctioning SDM.

AIR BAG Warning Lamp Comes On Steady

Step

Action

Value(s)

Yes

No

1

Did you perform the SIR Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - SIR

2

  1. Turn OFF the ignition.
  2. Install the scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool to request the SIR scan tool data list.

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. Use the scan tool to read the SIR scan tool data list.

Is IGNITION more than the specified value?

17.1 V

Go to Diagnostic System Check - Engine Electrical in Engine Electrical

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Inspect the inflatable restraint sensing and diagnostic module (SDM) wiring 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.

Did you complete the repair?

--

Go to Diagnostic System Check - SIR

--

6

  1. Disconnect the inflatable restraint steering wheel module coil and IP module yellow 2-way wiring harness connectors.
  2. Disconnect the SDM wiring harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Install the J 38715-96 SIR Shorting Bar Tool to the SDM wiring harness connector.
  4. Install the CPA.
  5. Turn ON the ignition, with the engine OFF.

Does the AIR BAG warning lamp come ON steady?

--

Go to Step 7

Go to Step 24

7

  1. Turn OFF the ignition.
  2. Remove the J 38715-96 from the SDM wiring harness connector.
  3. Inspect the shorting bar within the SDM wiring harness connector.

Is the shorting bar damaged or corroded?

--

Go to Step 8

Go to Step 9

8

Replace the SDM wiring harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 28

--

9

  1. Install the J 38715-96 to the SDM wiring harness connector.
  2. Install the CPA.
  3. Disconnect the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  4. Use the J 39200 Digital Multimeter (DMM) to measure the resistance between INFLATABLE RESTRAINT INDICATOR output of the SDM wiring harness connector and a known good ground.

Is the measured resistance less than the specified value?

OL

Go to Step 10

Go to Step 13

10

  1. Disconnect the ground circuit from G251. Refer to SIR Components .
  2. Use the J 39200 to measure the resistance between the inflatable restraint indicator circuit and the ground circuit of the SDM wiring harness connector.

Is the measured resistance less than the specified value?

OL

Go to Step 12

Go to Step 11

11
  1. Locate a short to ground in the inflatable restraint indicator circuit.
  2. Repair the short to ground in the inflatable restraint indicator circuit.

Did you complete the repair?

--

Go to Step 28

--

12
  1. Repair the short between the inflatable restraint indicator circuit and the ground circuit.
  2. Inspect the ground circuit for any cutting or chaffing.

Did you complete the repair?

--

Go to Step 28

--

13

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

Is the repair complete?

--

Go to Step 28

--

14

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

Is Fuse 21 good?

--

Go to Step 19

Go to Step 15

15

  1. Replace Fuse 21.
  2. Turn ON the ignition, with the engine OFF for 10 seconds.
  3. Turn OFF the ignition.
  4. Remove Fuse 21.
  5. Inspect Fuse 21.

Is Fuse 21 good?

--

Go to Step 18

Go to Step 16

16

  1. Disconnect the SDM wiring harness. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Use the J 39200 to measure the resistance between the output side of Fuse 21 and a known good ground.

Is the measured resistance less than the specified value?

OL

Go to Step 17

Go to Step 24

17
  1. Locate a short to ground in the ignition positive voltage circuit.
  2. Repair the short to ground in the ignition positive voltage circuit.
  3. Replace Fuse 21.

Did you complete the repair?

--

Go to Step 28

--

18

Install Fuse 21.

Did you complete the repair?

--

Go to Step 28

--

19

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

Is the connector secure?

--

Go to Step 21

Go to Step 20

20
  1. Properly connect the SDM wiring harness connector.
  2. Install the CPA.

Did you complete the repair?

--

Go to Step 28

--

21
  1. Disconnect the inflatable restraint steering wheel module coil and IP module yellow 2-way wiring harness connectors.
  2. Disconnect the SDM wiring harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Check the SDM wiring harness connector for a proper connection at the ignition positive voltage circuit input.

Is the SDM wiring harness connector damaged or corroded?

--

Go to Step 22

Go to Step 23

22

Replace the SDM wiring harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 28

--

23

Inspect the SDM terminals for damage or corrosion.

Are any terminals damaged or corroded?

--

Go to Step 24

Go to Step 25

24

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

Is the repair complete?

--

Go to Step 28

--

25

Use the J 39200 to measure the resistance between the output side of Fuse 21 and the ignition positive voltage circuit at the SDM wiring harness connector.

Is the measured resistance within the specified value?

0-2 ohms

Go to Step 27

Go to Step 26

26
  1. Locate an open or a high resistance in the ignition positive voltage circuit.
  2. Repair the open or the high resistance in the ignition positive voltage circuit.

Did you complete the repair?

--

Go to Step 28

--

27

  1. Turn ON the ignition, with the engine OFF.
  2. Use the J 39200 to measure the voltage between the input side of Fuse 21 and a known good ground.

Is the measured voltage within the specified value?

B+

Go to Step 24

Go to Power Distribution Schematics in Wiring Systems

28
  1. Reconnect all SIR components.
  2. Verify that all components and connectors are properly mounted.

Did you complete the action?

--

Go to Diagnostic System Check - SIR

--