For 1990-2009 cars

### Circuit Description

The SDM contains a sensing device which converts vehicle velocity changes to an electrical signal. The electrical signal generated is processed by the SDM and then compared to a value stored in memory. When the generated signal exceeds the stored value, additional signal processing is performed and the generated signals are compared to signals stored in memory. When two of the generated signals exceed the stored values, or when one of the generated signals exceeds the stored value and the internal SDM sensor closes, with loop faults present the SDM will cause current to flow through the inflator modules deploying the air bags and causing DTC B1053 to set.

### DTC Will Set When

The SDM detects a frontal crash up to 30 degrees off centerline of the vehicle, of sufficient force to warrant deployment of the air bags with loop faults present.

### Action Taken

SDM turns ON the AIR BAG telltale lamp, records "Crash Data" and sets DTC B1053 and DTC's B1015, B1021m, B1019 or B1025.

### DTC Will Clear When

The fault condition is removed, DTC B1053 will remain an active and history DTC, regardless if the ignition switch is turned OFF, or a Scan tool "Clear Codes" command is issued. the SDM must be replaced.

### Diagnostic Aids

It is critical to diagnose all circuitry before replacing the SDM. If a malfunction still exists, the new SDM may be damaged.

### Deployment Commanded with Deployment Loop Faults Present

When measurements are requested in this chart use SA 91114NE DVM with correct terminal adapter from SA 9206Z. When a check for proper connection is requested refer to Intermittent and Poor Connections. When a wire connector or terminal repair is requested, use the proper repair parts and refer to Wiring Repairs .

Caution: Be careful when you handle a sensing and diagnostic module (SDM). Do not strike or jolt the SDM. Before applying power to the SDM:

• | Remove any dirt, grease, etc. From the mounting surface.

• | Position the SDM horizontally on the mounting surface.

• | Tighten all of the SDM fasteners and SDM bracket fasteners to the specified torque value.

Failure to follow the correct procedures could cause air bag deployment, personal injury, or unnecessary SIR system repairs.

### DTC Chart Test Description

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

1. If inflator modules have not deployed, DTC B1053 may have set falsely.

2. If DTC B1053 has set with no signs of frontal impact, the diagnostic trouble code has set falsely.

3. This test checks for SDM malfunction setting the diagnostic trouble codes.

4. This test determines whether the diagnostic trouble code was set inadvertently during diagnosis.

5. When a frontal crash has occurred, it is necessary to perform the indicated procedures to ensure the SIR system is fully functional.

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - SIR? | Go to Step 2 | Go to SIR Diagnostic System Check
2 | Turn OFF ignition. Have inflator modules deployed? | Go to Step 5 | Go to Step 3
3 | Inspect front of vehicle and undercarriage for signs of impact. Are there signs of impact? | Go to Step 4 | Go to Step 6
4 | Any other diagnostic trouble codes present? |  |
5 |

1. Perform inspections as directed in Repairs and Inspections Required After Accident.
2. Replace SDM, inflator modules and other necessary components.
3. Clear SIR diagnostic trouble codes.
4. Repeat SIR Diagnostic System Check.

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6 |

1. Turn ON ignition.
2. Clear SIR diagnostic trouble codes.

Is DTC B1053 set?

7 |

1. Turn OFF ignition.
2. Replace SDM.
3. Reconnect all SIR system components. Ensure all components are properly mounted.
4. Repeat SIR Diagnostic System Check.

Go to Chart A

Go to Step 9

8 | Turn OFF ignition. Was DTC B1053 set when the SIR Diagnostic System Check was first performed. | Go to Step 8 | Go to Step 9
9 |

1. Replace SDM.
2. Reconnect all SIR system components. Ensure all components are properly mounted.

Repeat SIR Diagnostic System Check.

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10 | Repeat SIR Diagnostic System Check. | -- | --