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 checks the disable switch position switch and circuit defect by letting the regular voltage flow through the disable switch circuit and verifying the current.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1451 Manual Cut-off Switch Malfunction

### Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

### Conditions for Setting the DTC

An open or short in wiring between SDM and disable switch.

### 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 connector of the passenger disable switch.

Is the wiring and connector OK?

--

Go to Step 4

Go to Step 3

3 | Repair the wiring and connector of passenger disable switch. Is the repair complete? | -- | Go to Step 9 | --
4 |

1. Disconnect the passenger disable switch connector.
2. Disconnect the SDM connector.
3. Measure the resistance between terminal 60 of SDM and terminal 3 of disable switch.

Is the resistance as specified?

0 ohms

Go to Step 5

Go to Step 8

5 |

1. Connect the SDM connector.
2. Confirm the ignition switch is ON.
3. Measure the current at terminal 3 of disable switch.

Is the amperage higher than specified?

12.5 mA

Go to Step 6

Go to Step 7

6 | Replace the disable switch. Refer to Inflatable Restraint Instrument Panel Module Disable Switch Replacement . Is the replacement complete? | 10.6 V | 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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