GM Service Manual Online
For 1990-2009 cars only

Object Number: 172498  Size: SF
SIR Components
SIR Schematics

Circuit Description

When the ignition switch is first turned to the ON position, the IG-COIL METER fuse applies battery voltage to the AIR BAG warning lamp that is connected to the AIR BAG INDICATOR, terminal 7. The AIR BAG fuse applies battery voltage to the IGNITION 1 input, terminal 8. The inflatable restraint Sensing and Diagnostic Module (SDM) responds by flashing the AIR BAG warning lamp seven times.

When measurements are requested in this table, use J 39200 Digital Multimeter with the correct terminal adapter from J 35616 Connector Test Adapter Kit. When a check for proper connection is requested, refer to Intermittents and Poor Connections . When a wire, connector or terminal repair is requested, use J-38125 Terminal Repair Kit and refer to Wiring Repair in this section.

Test Description

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

  1. This test determines if the malfunction is in the inflatable restraint Sensing and Diagnostic Module (SDM) circuitry or in the instrument cluster power feed circuitry.

  2. This test determines if voltage is present in the warning lamp circuit.

  3. This test isolates the ORN wire to B+ and checks for a short in the ORN wire to B+.

  4. This test determines if the malfunction is in the instrument cluster connector.

  5. This test determines if the open is due to a malfunctioning bulb.

  6. This test isolates an open in the warning lamp circuitry.

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

  8. This test checks for a short from the instrument cluster power feed circuit to ground.

  9. This test determines whether the short to ground is due to a short in the wiring or internal to the instrument cluster.

  10. This test determines if the malfunction is in the instrument cluster connector.

  11. This test determines if the malfunction is due to an open power feed circuit from the IG-COIL METER Fuse.

AIR BAG Warning Lamp Does Not Come On

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

Observe the instrument cluster while turning the ignition switch to the ON position.

Does the BRAKE indicator come ON?

--

Go to Step 3

Go to Step 13

3

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the inflatable restraint steering wheel and inflatable restraint IP modules yellow connectors located under the steering wheel side cap and behind the IP compartment.
  3. Disconnect the inflatable restraint Sensing and Diagnostic Module (SDM).
  4. Install the J 38715-96 connector to the SDM harness connector.
  5. Turn the ignition switch to the ON position.
  6. Measure the voltage on the SDM harness connector from terminal 7 to ground.

Is the measured voltage more than the specified value?

10 V

Go to Step 4

Go to Step 6

4

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the instrument cluster. Refer to Instrument Panel, Gauges and Console.
  3. Turn the ignition switch to the ON position. Measure the voltage on the SDM harness connector from terminal 7 to ground.

Is the measured voltage less than the specified value?

1 V

Go to Integrity Check

Go to Step 5

5

  1. Turn the ignition switch to the LOCK position.
  2. Repair a short to B+ condition in the ORN wire.
  3. Reconnect the instrument cluster.

Is the circuit repair complete and the instrument cluster connected?

--

Go to Step 24

--

6

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the instrument cluster. Refer to Instrument Panel, Gauges and Console.
  3. Check for proper connection to the instrument cluster at connector C1 terminal 7.

Is the electrical harness connector damaged or corroded?

--

Go to Step 7

Go to Step 8

7

Repair the instrument cluster electrical harness connector. Refer to Electrical Diagnosis.

Did you repair the instrument cluster electrical harness connector?

--

Go to Step 24

--

8

  1. Remove the AIR BAG indicator bulb.
  2. Inspect the AIR BAG indicator bulb.

Is the AIR BAG indicator bulb good?

--

Go to Step 10

Go to Step 9

9

  1. Replace the AIR BAG indicator bulb.
  2. Install the instrument cluster.

Has the AIR BAG indicator bulb been replaced and the instrument cluster installed?

--

Go to Step 24

--

10

  1. Install the AIR BAG indicator bulb.
  2. Measure the resistance from the instrument cluster harness connector C1 terminal 7 to the SDM harness connector terminal 7.

Is the resistance reading within the specified values?

0 -5ohms

Go to Step 12

Go to Step 11

11

  1. Repair an open condition in the ORN wire.
  2. Install the instrument cluster.

Is the circuit repair complete and the instrument cluster installed?

--

Go to Step 24

--

12

  1. Service the instrument cluster.
  2. Install the instrument cluster.

Is the repair complete and the instrument cluster installed?

--

Go to Step 24

--

13

  1. Turn the ignition switch to the LOCK position.
  2. Remove the IG-COIL METER Fuse.
  3. Inspect the IG-COIL METER Fuse.

Is the IG-COIL METER Fuse good?

--

Go to Step 19

Go to Step 14

14

  1. Replace the IG-COIL METER Fuse.
  2. Turn the ignition switch to the ON position, wait 10 seconds, then turn the ignition switch to the LOCK position.
  3. Remove the IG-COIL METER Fuse.
  4. Inspect the IG-COIL METER Fuse.

Is the IG-COIL METER Fuse good?

--

Go to Step 18

Go to Step 15

15

  1. Disconnect the inflatable restraint steering wheel and the inflatable restraint IP modules yellow connectors located under the steering wheel side cap and behind the IP compartment.
  2. Disconnect the instrument cluster. Refer to Instrument Panel, Gauges and Console.
  3. Replace the IG-COIL METER Fuse.
  4. Turn the ignition switch to the ON position, wait 10 seconds, then turn the ignition switch to the LOCK position.
  5. Remove and inspect the IG-COIL METER Fuse.

Is the IG-COIL METER Fuse good?

--

Go to Step 17

Go to Step 16

16

  1. Repair a short to ground condition in the YEL/BLK wire.
  2. Replace the IG-COIL METER Fuse.

Is the circuit repair complete and the IG-COIL METER Fuse replaced?

--

Go to Step 24

--

17

  1. Service the instrument cluster.
  2. Install the instrument cluster.
  3. Install the IG-COIL METER Fuse.

Is the repair complete and the IG-COIL METER Fuse replaced?

--

Go to Step 24

--

18

Install the IG-COIL METER Fuse.

Did you install the IG-COIL METER Fuse?

--

Go to Step 24

--

19

  1. Disconnect the instrument cluster. Refer to Instrument Panel, Gauges and Console.
  2. Check for proper connection to the instrument cluster at connector C1 terminal 2.

Is the instrument cluster electrical harness connector damaged or corroded?

--

Go to Step 20

Go to Step 21

20

Repair the instrument cluster electrical harness connector. Refer to Instrument Cluster in Electrical Diagnosis.

Did you repair the instrument cluster electrical harness connector?

--

Go to Step 24

--

21

Measure the resistance from the instrument cluster harness connector C1 terminal 2, to each terminal of the IG-COIL METER Fuse fuseholder.

Is either resistance reading within the specified values?

0-5ohms

Go to Step 23

Go to Step 22

22

  1. Repair an open condition in the YEL/BLK wire.
  2. Install the IG-COIL METER Fuse.

Is the circuit repair complete and the IG-COIL METER Fuse installed?

--

Go to Step 24

--

23

  1. Repair an open condition in the power feed to the IG-COIL METER Fuse. Refer to Power Distribution in Electrical Diagnosis.
  2. Install the IG-COIL METER Fuse.

Is the circuit repair complete and the IG-COIL METER Fuse installed?

--

Go to Step 24

--

24

Reconnect all the SIR system components. Make sure all the components are properly mounted.

Are the SIR components connected and properly mounted?

--

Go to SIR Diagnostic System Check

--