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 B1478 Right Roof Rail Deployment Loop Resistance Low
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 deployment loop is lower than 1.77 ohms. |
| • | The shorting bar is damaged and the SDM must be replaced. |
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 | ||
2 |
Is the resistance equal to the specified value? | ∞ | Go to Step 3 | Go to Step 5 |
3 |
Is the DTC removed? | -- | Go to Step 6 | Go to Step 4 |
4 | Replace the right roof rail module. Is the replacement complete? | -- | Go to Step 6 | -- |
5 | Replace the air bag wiring. Is the replacement complete? | -- | Go to Step 6 | -- |
6 |
Does the DTC reset? | Go to Step 2 | System OK | |
