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

### Circuit Description

When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Next the SDM measures IGNITION and the deployment loop voltages to make sure they are within their respective normal voltage ranges. Then the SDM proceeds with the RESISTANCE MEASUREMENT test. During one portion of the RESISTANCE MEASUREMENT test, the SDM does the following:

• | Grounds the Driver Frontal Low terminal 2 through an internal current sink.

• | Connects the Driver Frontal High terminal 1 to an internal constant current source. This current produces proportional voltage drops in the deployment loop.

• | Measures the voltage difference between Driver Frontal High and Driver Frontal Low.

• | Calculates the resistance of the driver deployment loop using the measured voltage.

### Conditions for Setting the DTC

• | The driver and passenger frontal air bag deployment loops are not open.

• | The driver and passenger frontal air bag deployment loops are not shorted to voltage.

• | The driver frontal air bag deployment loop is not shorted to ground.

• | The driver frontal air bag deployment loop resistance is less than 1.9 ohm. The driver deployment loop consists of the following components:

- | Inflatable restraint steering wheel module.

- | Inflatable restraint steering wheel module coil.

- | Harness wiring of CKT 347.

- | Harness wiring of CKT 348.

- | Connector terminal contact.

The RESISTANCE MEASUREMENT test checks for this malfunction. This test only occurs once each ignition cycle when IGNITION is within the normal operating voltage range.

### Action Taken When the DTC Sets

• | The SDM sets a Diagnostic Trouble Code.

• | The SDM turns ON the AIR BAG warning lamp.

### Conditions for Clearing the DTC

• | Current DTC-The resistance of the driver deployment loop is more than 2.3 ohm and the ignition switch is cycled.

• | History DTC

- | You issue a scan tool CLEAR CODES command.

- | Once 250 malfunction free ignition cycles have occurred.

When you issue a scan tool CLEAR CODES command and the malfunction is still present, the DTC will not reappear until the next ignition cycle.

### Diagnostic Aids

The following can cause an intermittent condition:

• | A short circuit between CKT 347 and CKT 348.

• | A malfunctioning shorting bar on the inflatable restraint steering wheel module connector.

• | A malfunctioning shorting bar on the inflatable restraint steering wheel module coil steering column connector.

• | A malfunctioning shorting bar on the inflatable restraint sensing and diagnostic module (SDM) connector.

The diagnostic table directs the technician to note the entry value of DRIVER FRONTAL RESIST. Comparing the value of DRIVER FRONTAL RESIST. over multiple ignition cycles can be helpful in determining if an intermittent condition exists.

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 determines the deployment loop resistance measured by the inflatable restraintssensing and diagnostic module (SDM).

2. This test checks for proper contact or corrosion of the yellow 2-way connector.

3. This test isolates the malfunction to one side of the inflatable restraint steering wheel module yellow 2-way connector.

4. This test determines whether the malfunction is due to the inflatable restraint steering wheel module or the module coil.

5. This test checks for proper contact or corrosion of the SDM connector.

6. This test checks for a short between CKT 347 and CKT 348.

#### DTC B1022 Driver Deployment Loop Resistance Low

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 DLC.
3. Turn the ignition switch to the RUN position.
4. Request the SIR data list display.
5. Read and record on the repair order the driver frontal air bag deployment loop resistance DRIVER FRONTAL RESIST.

Has the DRIVER FRONTAL RESIST. been read and recorded on the repair order?

--

Go to Step 3

--

3 |

1. Turn the ignition switch to the OFF position.
2. 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.
3. Check for proper connection at terminals A and B on the harness side of the inflatable restraint steering wheel module yellow 2-way connector at the base of the steering column.

Are the terminals damaged or corroded?

--

Go to Step 4

Go to Step 6

4 | Replace the yellow 2-way harness connector at the base of the steering column. Refer to Wiring Repair . Are the repairs complete? | -- | Go to Step 5 | --
5 | Check for proper connection at terminals A and B of the inflatable restraint steering wheel module coil side of the connector. Are the terminals damaged or corroded? | -- | Go to Step 7 | Go to Step 21
6 | Check for proper connection at terminals A and B of the inflatable restraint steering wheel module coil side of the connector. Are the terminals damaged or corroded? | -- | Go to Step 7 | Go to Step 8
7 | Replace the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement . Are the repairs complete? | -- | Go to Step 21 | --
8 |

1. Connect the inflatable restraint steering wheel module and IP module yellow 2-way connectors located near the base of the steering column and behind the RH insulator panel.
2. Turn the ignition switch to the RUN position.
3. Using the scan tool, request the SIR data list display.
4. Read the driver frontal air bag deployment loop resistance DRIVER FRONTAL RESIST.

Is DRIVER FRONTAL RESIST. less than the specified value?

1.9 ohms

Go to Step 10

Go to Step 9

9 |

1. Turn the ignition switch to the OFF position.
2. Replace the yellow 2-way harness connector at the base of the steering column. Refer to Wiring Repair .

Are the repairs complete?

--

Go to Step 21

--

10 |

1. Turn the ignition switch to the OFF position.
2. 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.
3. Connect J 38715-A SIR Driver/Passenger Load Tool to the harness connectors.
4. Turn the ignition switch to the RUN position.
5. Using the scan tool, request the data list display.
6. Read the driver frontal air bag deployment loop resistance DRIVER FRONTAL RESIST.

Is DRIVER FRONTAL RESIST. less than the specified value?

1.9 ohms

Go to Step 14

Go to Step 11

11 |

1. Turn the ignition switch to the OFF position.
2. Remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
3. Disconnect J 38715-A from the driver 2-way harness connector.
4. Connect the 2-way connector at the base of the steering column.
5. Connect J 38715-A to the upper inflatable restraint steering wheel module coil connector on the steering column.
6. Turn the ignition switch to the RUN position.
7. Using the scan tool, request the SIR data list display.
8. Read the driver frontal air bag deployment loop resistance DRIVER FRONTAL RESIST.

Is DRIVER FRONTAL RESIST. less than the specified value?

1.9 ohms

Go to Step 13

Go to Step 12

12 |

1. Turn the ignition switch to the OFF position.
2. Replace the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .

Are the repairs complete?

--

Go to Step 21

--

13 |

1. Turn the ignition switch to the OFF position.
2. Replace the inflatable restraint steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Are the repairs complete?

--

Go to Step 21

--

14 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
3. Disconnect J 38715-A .
4. Check for proper connection at terminal 1 and terminal 2 on the harness side of the SDM connector.

Is the connector damaged or corroded?

--

Go to Step 15

Go to Step 17

15 | Replace the SDM connector. Refer to Wiring Repair . Are the repairs complete? | -- | Go to Step 16 | --
16 | Check for proper connection at terminal 1 and terminal 2 on the SDM. Are the terminals damaged or corroded? | -- | Go to Step 18 | Go to Step 21
17 | Check for proper connection at terminal 1 and terminal 2 on the SDM. Are the terminals damaged or corroded? | -- | Go to Step 18 | Go to Step 19
18 | 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 21 | --
19 |

1. Insert the J 42113 SIR shorting bar tool into the SDM harness connector above terminals 1 and 2.
2. Zero the J 39200 Digital Multimeter.
3. Measure the resistance from the inflatable restraint steerring wheel module harness connector terminal A to terminal B.

Is the resistance reading within the specified values?

0-0.5 ohms

Go to Step 20

Go to Integrity Check

20 | Repair the short between CKT 347 and CKT 348. Are the repairs complete? | -- | Go to Step 21 | --
21 | 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 Step 22 | --
22 | Clear all the SIR DTCs. Have all the SIR DTCs been cleared? | -- | Go to SIR Diagnostic System Check | --