For 1990-2009 cars
SIR Components
SIR Schematics
Handling ESD Sensitive Parts Notice
SIR Caution
Handling ESD Sensitive Parts Notice

### Circuit Description

When the ignition switch is first turned to the RUN position, the IGN 1 Fuse applies battery voltage to the AIR BAG warning lamp that is connected to INFLATABLE RESTRAINT INDICATOR, terminal 6. The SIR Fuse applies battery voltage to the IGNITION input, terminal 5. The inflatable restraint sensing and diagnostic module (SDM) responds by flashing the AIR BAG warning lamp seven times. If IGNITION is outside of the normal operating voltage range (9 volts - 16 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 SDM harness connector must be properly connected to the SDM.

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 .

### Test Description

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

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

2. This test checks for excessive IGNITION voltage applied to the SDM.

3. This test checks for a properly installed CPA.

4. This test determines if the SDM is turning on the AIR BAG warning lamp.

5. This test checks for a damaged shorting bar.

6. This test determines whether the malfunction is a short to ground in CKT 358.

7. This test checks for a short between CKT 358 and CKT 1751.

8. An open SIR Fuse would cause the AIR BAG warning lamp to come on steady.

9. This test checks whether a short to ground caused the SIR Fuse to open.

10. This test determines whether the short to ground is due to a short in the wiring or internal to the SDM.

11. This test checks for a disconnected SDM.

12. This test checks for an open in the IGNITION 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
2 |

1. Turn the ignition switch to the OFF position.
2. Connect a 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?

9 V

Go to Step 3

Go to Step 14

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?

16 V

Go to Charging System Check in Engine Electrical

Go to Step 4

4 |

1. Turn the ignition switch to the OFF position.
2. Inspect the inflatable restraint Sensing and Diagnostic Module (SDM) harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Is the SDM harness connector properly connected and the CPA properly installed?

--

Go to Step 6

Go to Step 5

5 | Properly connect the SDM harness connector and install the CPA. Are the repairs complete? | -- | Go to SIR Diagnostic System Check | --
6 |

1. Disconnect the inflatable restraint steering wheel module and inflatable restraint IP module yellow 2-way connector located near the base of the steering column and behind the RH insulator panel.
2. Disconnect the SDM harness connector.
3. Insert the J 42113 SIR Shorting Bar Tool into the SDM harnrss connector above terminals 6 and 7.
4. Turn the ignition switch to the RUN position.

Does the AIR BAG warning lamp come ON steady?

--

Go to Step 7

Go to Integrity Check

7 |

1. Turn the ignition switch to the OFF position.
2. Remove J 42113 SIR Shorting Bar Tool from the SDM harness connector.
3. Inspect the shorting bar across terminals 6 and 7 within the SDM harness connector.

Is the shorting bar damaged or corroded?

--

Go to Step 8

Go to Step 9

8 | Replace the SDM connector. Refer to Wiring Repair . Are the repairs complete? | -- | Go to Step 28 | --
9 |

1. Insert the J 42113 SIR Shorting Bar Tool into the SDM harnrss connector above terminals 6 and 7.
2. Disconnect the instrument cluster. Refer to IP Cluster Replacement in Instrument Panel, Gages and Console.
3. Measure the resistance from the SDM harness connector terminal 6 to ground.

Is the resistance reading less than the specified value?

OL

Go to Step 10

Go to Step 13

10 |

1. Disconnect CKT 1751 from G302. Refer to SIR Components .
2. Measure the resistance from the SDM harness connector terminal 6 to terminal 7.

Is the resistance reading less than the specified value?

OL

Go to Step 12

Go to Step 11

11 | Repair a short to ground condition in CKT 358. Are the repairs complete? | -- | Go to Step 28 | --
12 |

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

Are the repairs complete?

--

Go to Step 28

--

13 | Service the instrument cluster. Refer to IP Cluster Replacement in Instrument Panel, Gages and Console. Are the repairs complete? | -- | Go to Step 28 | --
14 |

1. Turn the ignition switch to the OFF position.
2. Remove the SIR Fuse.
3. Inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 20

Go to Step 15

15 |

1. Replace the SIR 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 SIR Fuse.
5. Inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 19

Go to Step 16

16 |

1. Disconnect the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
2. Replace the SIR 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 SIR Fuse.
6. Inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 18

Go to Step 17

17 |

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

Are the repairs complete?

--

Go to Step 28

--

18 |

1. Replace the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
2. Install the SIR Fuse.

Are the repairs complete?

--

Go to Step 28

--

19 | Install the SIR Fuse. Are the repairs complete? | -- | Go to Step 28 | --
20 | Inspect the SDM harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Is the connector secure? | -- | Go to Step 22 | Go to Step 21
21 | Properly connect the SDM harness connector and CPA. Are the repairs complete? | -- | Go to Step 28 | --
22 |

1. Disconnect the inflatable restraint steering wheel and IP module yellow 2-way connectors located near the base of the steering column and behind the RH insulator panel.
2. Disconnect the SDM.
3. Check for proper connection to the SDM at terminal 5.

Is the SDM harness connector terminal damaged or corroded?

--

Go to Step 23

Go to Step 24

23 | Replace the SDM connector. Refer to Wiring Repair . Are the repairs complete? | -- | Go to Step 28 | --
24 | Inspect the SDM terminals for damage or corrosion. Are any terminals damaged or corroded? | -- | Go to Step 25 | Go to Step 26
25 | Replace the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Are the repairs complete? | -- | Go to Step 28 | --
26 | Measure the resistance from the SDM harness connector terminal 10 to each terminal of Fuse 21 fuseholder. Is either resistance reading within the specified values? | 0-5 ohms | Go to Integrity Check | Go to Step 27
27 | Repair an open condition in CKT 1139. Are the repairs complete? | -- | Go to Step 28 | --
28 | 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 | --