For 1990-2009 cars

### Circuit Description

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

Upon passing these tests, ignition and deployment loop voltages are measured to ensure that they are within their normal voltage ranges. The SDM monitors the voltages at the driver low and the passenger low to detect shorts to ground or voltage in the deployment loops.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1477 Right Roof Rail Deployment Loop Resistance Above Threshold

### Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

### Conditions for Setting the DTC

The resistance of the right roof rail air bag deployment loop is higher than 3.54 ohms.

### 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 | Visually inspect the connector and the wiring of the driver side air bag. Is the wiring damaged? | -- | Go to Step 4 | Go to Step 3
3 |

1. Confirm the ignition switch is OFF.
2. Disconnect the connector of the left roof rail module.
3. Disconnect the connector of the sensing and diagnostic module (SDM) wiring.
4. Measure the resistance between terminal 47, 48 of the SDM and terminal 1, 2 of the right roof rail module connector.

Is the resistance equal to the specified value?

0 ohms

Go to Step 5

Go to Step 4

4 | Repair the open or high resistance. Did you complete the repair? | -- | Go to Step 7 | --
5 |

1. Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
2. Confirm the ignition switch is ON.
3. Erase the DTC using the scan tool.
4. Perform the Diagnostic System Check - Vehicle .

Is the DTC removed?

--

Go to Step 7

Go to Step 6

6 | Replace the right roof rail module. Is the replacement complete? | -- | Go to Step 7 | --
7 |

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

System OK