Circuit Description
When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform tests to diagnose critical malfunctions within the SDM itself.
After passing these tests, ignition and deployment loop voltages are measured to ensure that they are within their respective normal voltage ranges. The SDM then proceeds with the resistance measurement test.
Each inflator low terminal is grounded through a current sink, and each inflator current source is connected to each inflator high terminal to allow a known amount of current to flow.
By monitoring the voltage difference between each inflator high and low, the SDM calculates the combined resistance of the inflator module, the wiring harness and the connector terminal contacts.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC B0040 LF Side Deployment Loop Resistance Low |
| • | DTC B0041 LF Side Deployment Loop Open Circuit |
| • | DTC B0045 LF Side Deployment Loop Voltage Out of Range |
Conditions for Running the DTC
Ignition voltage is within the normal operating voltage range.
Conditions for Setting the DTC
| • | DTC B0040 will set when the SDM detects the resistance of driver side air bag deployment loop is lower than 1.3 ohms. |
| • | DTC B0041 will set when the SDM detects the resistance of driver side air bag deployment loop is higher than 4.8 ohms for 5 consecutive test cycles. |
| • | DTC B0045 will set when the SDM detects the resistance of driver side high is greater than 7.5 volts for 5 consecutive test cycles, or voltage at the driver side high is less than 1.5 volts and resistance of the driver side deployment loop is less than 6 ohms for 5 consecutive test cycles. |
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.
Diagnostic Aids
| • | DTC B0040, an intermittent condition is likely to be caused by a short between the driver side high and low circuits. |
| • | DTC B0041, an intermittent condition is likely to be caused by a poor connection at the air bag connector or SDM. |
| • | DTC B0045, an intermittent condition is likely to be caused by a short to ground or voltage in the driver side high and low circuits. |
Step | Action | Yes | No |
|---|---|---|---|
|
Warning: Refer to SIR Warning in the Preface section. Schematic Reference: SIR Schematics Connector End View Reference: Component Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Is DTC B0040, B0041, or B0045 set as a current DTC? | Go to Step 3 | Go to Diagnostic Aids |
3 |
Is the connector disconnected or wiring damaged? | Go to Step 4 | Go to Step 5 |
4 | Connect the driver side air bag module connector or replace the wiring. Is the repair complete? | Go to Step 9 | -- |
5 |
For all the above conditions, refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
6 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement. Did you complete the replacement? | Go to Step 7 | -- |
7 |
Does the DTC reset? | Go to Step 8 | System OK |
8 | Replace the driver side air bag module. Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does the DTC reset? | Go to Step 2 | -- |
