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

### 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. Upon passing these tests IGNITION 1, 23VLR and the deployment loop voltages are measured to make sure they are within their respective normal voltage ranges. The SDM monitors the voltages at DRIVER SENSE LOW terminal 3 and PASSENGER SENSE LOW terminal 4 to detect shorts to ground in the inflator module circuits. The service wait time is 10 minutes. Refer to ENABLE/DISABLE 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 SENSE LOW terminal 4 is more than 3.3 volts.

• | The voltage at DRIVER SENSE 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 lamp.

### Conditions for Clearing the MIL/DTC

DTC B1024 is a latched code. You cannot 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 can cause an intermittent condition. A DTC B1024 would be accompanied by DTC B1071. Inspect CKT 347 and CKT 348 carefully for cutting or chafing. 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 to note the entry value of DRIVER SENSELO. Comparing the value of DRIVER SENSELO can be helpful in determining if an intermittent condition exists.

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 the driver side low voltage measured by the inflatable restraint sensing and diagnostic module (SDM).

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

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

4. This test determines whether the malfunction is in CKT 347.

5. This test determines whether the malfunction is in CKT 348.

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.

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

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Caution: The SIR driver deployment loop (circuits 347 and 348) passes through connector C200. You must take special precautions before servicing C200. Disable the SIR system before you disconnect, probe or service connector C200. Refer to Disabling the SIR System in SIR. Failure to follow the correct procedures could cause air bag deployment, personal injury or unnecessary SIR system repairs.
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 side low voltage DRIVER SENSELO.

Has the DRIVER SENSELO 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 under the RH I/P.
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 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 J 38715-A from the driver 2-way harness connector.
4. Connect the driver 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 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 (driver inflator module). Refer to Inflatable Restraint Steering Wheel Module Replacement .

Are the repairs 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 (SIR coil assembly). Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Are the repairs 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. Disconnect the J 38715-A .
4. Measure the resistance on the SDM harness connector from terminal 2 to terminal 6 (ground).

Is the resistance reading less than the specified value?

OL

Go to Step 8

Go to Step 9

8 | Repair a short to ground condition in CKT 347. Are the repairs complete? | -- | Go to Step 11 | --
9 | Measure the resistance on the SDM harness connector from terminal 3 to terminal 6 (ground). Is the resistance reading less than the specified value? | OL | Go to Step 10 | Go to Integrity Check
10 | Repair a short to ground condition in CKT 348. Are the repairs complete? | -- | Go to Step 11 | --
11 |

1. Reconnect all the SIR system components, make 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

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