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

### Circuit Description

When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests in order to diagnose critical malfunctions within the module. Upon passing these tests, the ignition positive voltage, the 23 VLR and the deployment loop voltages are measured in order to ensure that the voltages are within the respective normal voltage ranges. The SDM monitors the voltages at the DRIVER LOW terminal 3 and the PASSENGER LOW terminal 4 in order to detect shorts to ground in the inflator module circuits. The service wait time is 10 minutes. Refer to Disabling the SIR System or Enabling the SIR System for procedures.

### Conditions for Setting the DTC

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

• | The passenger deployment loop is not shorted to voltage.

• | The voltage at PASSENGER LOW terminal 4 is more than 3.3 volts.

• | The voltage at DRIVER LOW terminal 3 is less than 3.3 volts for 500 milliseconds.

The following tests check for this DTC. These tests occur when IGNITION 1 is within the normal operating voltage range.

• | Power on

| When the malfunction is detected in this test, the resistance measurement test will not be performed.

• | Continuous monitoring

### Action Taken When the DTC Sets

• | The SDM sets DTC B1024 and also DTC B1071.

• | The SDM turns ON the AIR BAG Warning Indicator.

### Conditions for Clearing the MIL/DTC

DTC B1024 is a latched code. You may not clear a latched code. Repair the malfunction that set this DTC before you replace the SDM.

### Diagnostic Aids

A short to ground in the inflatable restraint steering wheel module circuit may cause an intermittent condition. A DTC B1024 may be accompanied by DTC B1071. Carefully inspect CKT 347 and CKT 348 for cut or chafed wires. A careful inspection of the circuits and components indicated on the DTC B1024 table is essential in order to prevent damage to the replacement inflatable restraint sensing and diagnostic module (SDM). The diagnostic table directs the technician in order to note the entry value of the DRIVER SENSELO. Comparing the value of the DRIVER SENSELO may 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 step checks the driver side low voltage that was measured by the inflatable restraint sensing and diagnostic module (SDM). A reading of 3.3 V or more indicates that an intermittent condition may exist.

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

3. This step determines if there is a malfunctioning inflatable restraint steering wheel module coil or if there is a malfunctioning inflatable restraint steering wheel module.

4. This step checks to see if there is a short to ground in CKT 347.

5. This step determines if there is a short to ground in CKT 348 or if there is a malfunctioning SDM.

#### DTC B1024 Driver Deployment Loop Short to Ground

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Notice: When DTC B1018 or B1024 has been set it is necessary to replace the inflatable restraint Sensing and Diagnostic Module (SDM). Setting DTC B1018 or B1024 will also cause DTC B1071 to set. When a scan tool clear codes command is issued and the malfunction is no longer present, DTC B1018 or B1024 and DTC B1071 will remain current. Make sure that the short to ground condition is repaired prior to installing a replacement SDM to avoid damaging the SDM.
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 the scan tool.
3. Turn the ignition switch to the RUN position.
4. Use the scan tool to request the SIR data list display.
5. Read and record on the repair order the driver side low voltage DRIVER SENSELO.

Is the DRIVER SENSELO less than the specified value?

3.3 V

Go to Step 3

Go to Diagnostic Aids

3 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the inflatable restraint steering wheel and IP module yellow 2-way wiring harness connectors at the base of the steering column and behind the IP compartment door.
3. Connect the J 38715-A SIR Diver/Passenger Load Tool to the IP wiring harness connectors.
4. Turn the ignition switch to the RUN position.
5. Use the scan tool to request the SIR data list display.
6. Read the driver side low voltage DRIVER SENSELO.

Is DRIVER SENSELO less than the specified value?

3.3 V

Go to Step 7

Go to Step 4

4 |

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 the J 38715-A Load Tool from the driver yellow 2-way wiring harness connector.
4. Connect the driver 2-way connector at the base of the steering column.
5. Connect the J 38715-A Load Tool to the upper inflatable restraint steering wheel module coil connector on the steering column.
6. Turn the ignition switch to the RUN position.
7. Use the scan tool to request the SIR data list display.
8. Read the driver side low voltage DRIVER SENSELO.

Is DRIVER SENSELO less than the specified value?

3.3 V

Go to Step 6

Go to Step 5

5 |

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

Is the repair complete?

--

Go to Step 11

--

6 |

1. Turn the ignition switch to the OFF position.
2. Remove the inflatable restraint steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .
3. Inspect the coil and the wires for damage.
4. Replace the inflatable restraint steering wheel module coil if any damage if found.

Is the repair complete?

--

Go to Step 11

--

7 |

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. Remove the J 38715-A Load Tool from the IP wiring harness connectors.
4. Use J 39200 DMM, measure the resistance between terminals 2 and 6 of the SDM wiring harness connector.

Is the measured resistance less than the specified value?

OL

Go to Step 8

Go to Step 9

8 |

1. Locate a short to ground in CKT 347.
2. Repair the short to ground in CKT 347.

Is the repair complete?

--

Go to Step 11

--

9 | Use J 39200 DMM, measure the resistance between terminals 3 and 6 of the SDM wiring harness connector. Is the measured resistance less than the specified value? | OL | Go to Step 10 | Go to Sensing and Diagnostic Module Integrity Check
10 |

1. Locate a short to ground in CKT 348.
2. Repair the short to ground in CKT 348.

Is the repair complete?

--

Go to Step 11

--

11 |

1. Reconnect all the SIR system components, making sure all the components are properly mounted.
2. Turn the ignition switch to the RUN position.
3. Make sure that DRIVER SENSELO is more than the specified value.
4. Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement

Have all the SIR components been reconnected and properly mounted?

3.3 V

Go to SIR Diagnostic System Check

--