GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Monte Carlo 🢒 Restraints 🢒 SIR 🢒 AIR BAG Warning Lamp Does Not Come On

Object Number: 420641 Size: SF
SIR Components
Cell 47: SIR Diagnostic Module, Seat Belt Switch
SIR Caution
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The ignition switch supplies IGNITION 1 voltage to the inflatable restraint sensing and diagnostic module (SDM) at terminal 10 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 terminal 7 of 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.

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

    3.

  3. This step checks to see if there is a short to B+ in CKT 358.

    4.

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

    5.

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

    6.

  6. This step checks to see if there is an open or a high resistance in CKT 358.

    7.

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

    8.

  8. This step checks to see if there is a short to ground in CKT 39.

    9.

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

    10.

  10. This step determines if there is an open or a high resistance in CKT 39 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

Was the SIR Diagnostic System Check performed?

--

Go to Step 2

Go to SIR Diagnostic System Check

2

  1. Set the parking brake.
  2. Turn the ignition switch to the RUN position.

Does the BRAKE indicator light?

--

Go to Step 3

Go to Step 13

3

  1. Turn the ignition switch to the OFF position.
  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 the ignition switch to the RUN position.
  7. Use the J 39200 Digital Multimeter (DMM) to measure the voltage between terminal 7 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 the ignition switch to the OFF position.
  2. Disconnect the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  3. Turn the ignition switch to the RUN position.
  4. Use the J 39200 to measure the voltage between terminal 7 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 Sensing and Diagnostic Module Integrity Check

Go to Step 5

5
  1. Turn the ignition switch to the OFF position.
  2. Locate a short to B+ in CKT 358.
  3. Repair the short to B+ in CKT 358.
  4. Reconnect the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Is the repair complete?

--

Go to Step 24

--

6

  1. Turn the ignition switch to the OFF position.
  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 terminal C15.

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.

Is the repair complete?

--

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.

Is the repair complete?

--

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 between terminal C15 of the instrument cluster wiring harness connector and terminal 7 of 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 CKT 358.
  2. Repair the open or the high resistance in CKT 358.
  3. Install the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Is the repair complete?

--

Go to Step 24

--

12

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

Is the repair complete?

--

Go to Step 24

--

13

  1. Turn the ignition switch to the OFF position.
  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 the ignition switch to the RUN position for 10 seconds.
  3. Turn the ignition switch to the OFF position.
  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 between terminal C1 of 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 CKT 39.
  2. Repair the short to ground in CKT 39.
  3. Replace Fuse 39.

Is the repair complete?

--

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.

Is the repair complete?

--

Go to Step 24

--

18

Install Fuse 39.

Is the repair complete?

--

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 terminal C1.

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.

Is the repair complete?

--

Go to Step 24

--

21

Use the J 39200 to measure the resistance between terminal C1 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 CKT 39.
  2. Repair the open or the high resistance in CKT 39.
  3. Install Fuse 39.

Is the repair complete?

--

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.

Is the repair complete?

--

Go to Step 24

--

24

Reconnect all the SIR system components, making sure all the components are properly mounted.

Have all the SIR components been reconnected and properly mounted?

--

Go to SIR Diagnostic System Check

--