For 1990-2009 cars

### Circuit Description

When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform turn-on test to diagnose critical malfunctions within SDM itself.

The SDM continuously receives vehicle speed signal from the cluster. If driver seat belt is unbelted, the SDM gives the such alerts as warning lamp and sound according to vehicle status.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1453 VSS Incorrect

### Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

### Conditions for Setting the DTC

The SDM can not receive vehicle speed signal from the cluster.

### Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON.

### Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section. Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section. Schematic Reference: SIR Schematics Connector End View Reference: SIR Connector End Views
1 | Did you perform a Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Confirm the ignition switch is OFF.
2. Wait one minute for sensing and diagnostic module (SDM) to discharge.
3. Visually inspect the wiring and connectors between the SDM and the cluster.

Is the wiring and connector OK?

--

Go to Step 4

Go to Step 3

3 | Repair the wiring and connector between the SDM and the cluster. Is the repair complete? | -- | Go to Step 9 | --
4 |

1. Confirm the ignition switch is OFF.
2. Wait one minute for SDM to discharge.
3. Disconnect the cluster connector.
4. Disconnect the SDM connector.
5. On North America vehicles, measure the resistance between terminal 57 of SDM and terminal B3 of the cluster.
6. On all except North America Vehicles, measure the resistance between terminal 57 of SDM and terminal B14 of the cluster.

Is the resistance as specified?

0 ohms

Go to Step 5

Go to Step 8

5 | Measure the resistance between terminal 57 of SDM and ground. Is the as specified? | ∞ | Go to Step 6 | Go to Step 8
6 |

1. Replace the cluster. Refer to Inflatable Restraint Instrument Panel Module Disable Switch Replacement .
2. Reconnect all SIR components.
3. Verify that all components, connectors and connector position assurances (CPAs) are properly mounted.
4. Use the scan tool in order to clear the DTCs.
5. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

10.6 V

Go to Step 7

Go to Step 9

7 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Is the replacement complete? |  | Go to Step 9 | --
8 | Replace the airbag wiring. Is the replacement complete? | -- | Go to Step 9 | --
9 |

1. Reconnect all SIR components.
2. Verify that all components, connectors and connector position assurances (CPAs) are properly mounted.
3. Use the scan tool in order to clear the DTCs.
4. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

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