GM Service Manual Online
For 1990-2009 cars only

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) at 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 by the inflatable restraint indicator circuit at the SDM. When the ignition switch is first turned to RUN, the SDM responds by flashing the AIR BAG warning lamp seven times.

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 determines whether the malfunction is in the inflatable restraint sensing and diagnostic module (SDM) circuitry or in the instrument cluster power feed circuitry.

  2. This step checks to see if voltage is present in the AIR BAG warning lamp circuit.

  3. This step checks to see if there is a short to B+ in the inflatable restraint indicator circuit.

  4. This step checks to see if the instrument cluster wiring harness connector is damaged or corroded.

  5. This step checks to see if the open is due to a bad bulb.

  6. This step checks to see if there is an open or a high resistance in the inflatable restraint indicator circuit.

  7. This step checks to see if power is available to the instrument cluster power feed circuit.

  8. This step checks to see if there is a short to ground in the air bag warning indicator circuit.

  9. This step checks to see if the instrument cluster wiring harness connector is damaged or corroded.

  10. This step determines if there is an open or a high resistance in the air bag warning indicator circuit or if there is an open or a high resistance in the power feed circuit to fuse 39.

Air Bag Warning Lamp Does Not Come On

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. Set the parking brake.
  2. Turn ON the ignition, with the engine OFF.

Does the BRAKE indicator light?

--

Go to Step 3

Go to Step 13

3

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint steering wheel module coil and IP module yellow 2-way wiring harness connectors.
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Install the J 38715-96 SIR Shorting Bar Tool to the SDM wiring harness connector.
  5. Install the CPA.
  6. Turn ON the ignition, with the engine OFF.
  7. Use the J 39200 Digital Multimeter (DMM) to measure the voltage between the inflatable restraint indicator circuit of the SDM wiring harness connector and a known good ground.

Is the measured voltage more than the specified value?

10.0 V

Go to Step 4

Go to Step 6

4

  1. Turn OFF the ignition.
  2. Disconnect the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the J 39200 to measure the voltage between the inflatable restraint indicator circuit of the SDM wiring harness connector and a known good ground.

Is the measured voltage less than the specified value?

1.0 V

Go to Inflatable Restraint Sensing and Diagnostic Module Replacement

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Locate a short to B+ in the inflatable restraint indicator circuit.
  3. Repair the short to B+ in inflatable restraint indicator circuit.
  4. Reconnect the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Did you complete the repair?

--

Go to Step 24

--

6

  1. Turn OFF the ignition.
  2. Remove the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  3. Check the instrument cluster wiring harness connector for a proper connection at the inflatable restraint indicator circuit.

Is the connector damaged or corroded?

--

Go to Step 7

Go to Step 8

7

Repair the instrument cluster wiring harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

--

8

  1. Remove the AIR BAG warning lamp bulb. Refer to Instrument Cluster Bulb Replacement in Instrument Panel, Gages and Console.
  2. Inspect the AIR BAG warning lamp bulb.

Is the AIR BAG warning lamp bulb good?

--

Go to Step 10

Go to Step 9

9

  1. Replace the AIR BAG warning lamp bulb. Refer to Instrument Cluster Bulb Replacement in Instrument Panel, Gages and Console.
  2. Install the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Did you complete the repair?

--

Go to Step 24

--

10

  1. Install the AIR BAG warning lamp bulb. Refer to Instrument Cluster Bulb Replacement in Instrument Panel, Gages and Console.
  2. Use the J 39200 to measure the resistance of the inflatable restraint indicator circuit between the instrument cluster wiring harness connector and the SDM wiring harness connector.

Is the measured resistance within the specified values?

0-2 ohms

Go to Step 12

Go to Step 11

11

  1. Locate an open or a high resistance in the inflatable restraint indicator circuit.
  2. Repair the open or the high resistance in the inflatable restraint indicator circuit.
  3. Install the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Did you complete the repair?

--

Go to Step 24

--

12

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

Did you complete the repair?

--

Go to Step 24

--

13

  1. Turn OFF the ignition.
  2. Remove Fuse 39.
  3. Inspect the fuse.

Is the fuse good?

--

Go to Step 19

Go to Step 14

14

  1. Replace the fuse.
  2. Turn ON the ignition, with the engine OFF for 10 seconds.
  3. Turn OFF the ignition.
  4. Remove Fuse 39.
  5. Inspect the fuse.

Is the fuse good?

--

Go to Step 18

Go to Step 15

15

  1. Disconnect the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  2. Use the J 39200 to measure the resistance of the air bag warning indicator circuit between the instrument cluster wiring harness connector and a known good ground.

Is the measured resistance less than the specified value?

OL

Go to Step 16

Go to Step 17

16

  1. Locate a short to ground in the air bag warning indicator circuit.
  2. Repair the short to ground in the air bag warning indicator circuit.
  3. Replace Fuse 39.

Did you complete the repair?

--

Go to Step 24

--

17

  1. Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  2. Install Fuse 39.

Did you complete the repair?

--

Go to Step 24

--

18

Install Fuse 39.

Did you complete the repair?

--

Go to Step 24

--

19

  1. Remove the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  2. Check the instrument cluster wiring harness connector for a proper connection at the air bag warning indicator circuit.

Is the connector damaged or corroded?

--

Go to Step 20

Go to Step 21

20

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

Did you complete the repair?

--

Go to Step 24

--

21

Use the J 39200 to measure the resistance between the air bag warning indicator circuit of the instrument cluster wiring harness connector and each terminal of the Fuse 39 fuseholder.

Is the measured resistance for either measurement within the specified value?

0-2 ohms

Go to Step 23

Go to Step 22

22

  1. Locate an open or a high resistance in the air bag warning indicator circuit.
  2. Repair the open or the high resistance in the air bag warning indicator circuit.
  3. Install Fuse 39.

Did you complete the repair?

--

Go to Step 24

--

23

  1. Repair an open or a high resistance in the power feed circuit to Fuse 39.
  2. Install Fuse 39.

Did you complete the repair?

--

Go to Step 24

--

24

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

Did you complete the action?

--

Go to Diagnostic System Check - SIR

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