For 1990-2009 cars

### Circuit Description

The inflatable restraint sensing and diagnostic module (SDM) contains sensing devices that convert vehicle velocity changes to electrical signals. The SDM processes the generated electrical signals and compares them to values stored in memory. When the generated signals exceed the stored values, the SDM performs additional signal processing and compares the generated signals to signals stored in memory. When 2 of the generated signals exceed the stored values, the SDM will cause current to flow through the inflator modules, deploying the inflator modules. Diagnostic trouble code (DTC) B0053 will set along with DTC B0051 when a deployment occurs while a circuit malfunction is present in any one of the deployment loops.

### Conditions for Running the DTC

Ignition 1 voltage is within the normal operating voltage range.

### Conditions for Setting the DTC

The DTC will set if one of the following conditions occurs:

• | The SDM detects a frontal crash of sufficient force to warrant deployment of the frontal inflator modules.

• | The SDM detects a side impact crash of sufficient force to warrant deployment of a roof rail inflator module.

### Action Taken When the DTC Sets

• | The SDM sets DTC B0051.

• | The SDM commands the AIR BAG indicator ON via Class 2 serial data.

• | The SDM records crash data.

### Conditions for Clearing the DTC

DTC B0053 is a latched code. You cannot clear a latched code. Replace the SDM after following the instructions in the diagnostic table.

### Diagnostic Aids

DTC B0053 will be accompanied by another DTC, other than DTC B1000 and DTC B0051. Repair the malfunction causing the other DTCs before installing a new SDM.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: SIR Schematics
1 | Did you perform the Diagnostic System Check - SIR? | Go to Step 2 | Go to Diagnostic System Check - SIR
2 |

1. Turn OFF the ignition.
2. Inspect the vehicle for signs of inflator module deployment.

Does the vehicle show any signs of inflator module deployment?

Go to Step 5

Go to Step 3

3 | Inspect the front of the vehicle and undercarriage for signs of impact/collision. Does the vehicle show any signs of impact/collision? | Go to Step 5 | Go to Step 4
4 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you complete the replacement? | Go to Step 6 | --
5 |

1. Install a scan tool.
2. With a scan tool, observe the SIR DTC display.
3. If a history DTC exists, refer to Diagnostic Aids for that specific DTC and diagnose the problem.
4. Replace components and perform inspections as required following an accident. Refer to Repairs and Inspections Required After a Collision .

Did you complete the action?

Go to Step 6

--

6 |

1. Reconnect all SIR components.
2. Use the scan tool in order to clear the DTCs.
3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK