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 B0022 Driver Frontal Deployment Loop Resistance Low |
| • | DTC B0024 Driver Frontal Deployment Loop Voltage Out of Range |
| • | DTC B0026 Driver Frontal Deployment Loop Open |
Conditions for Running the DTC
Ignition voltage is within the normal operating voltage range.
Conditions for Setting the DTC
| • | DTC B0022 will set when the SDM detects the resistance of steering wheel module deployment loop is lower than 1.3 ohms. |
| • | DTC B0024 will set when the SDM detects the resistance of steering wheel module high is greater than 7.5 volts for 5 consecutive test cycles, or voltage at the steering wheel module high is less than 1.5 volts and resistance of the steering wheel module deployment loop is less than 6 ohms for 5 consecutive test cycles. |
| • | DTC B0026 will set when the SDM detects the resistance of steering wheel module deployment loop is higher than 4.8 ohms for 5 consecutive test cycles, or voltage at the steering wheel module high is less than 2.4 volts and resistance of the steering wheel module deployment loop is 6 or more 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 B0022, an intermittent condition is likely to be caused by a short between the steering wheel module high and low circuits. |
| • | DTC B0024, an intermittent condition is likely to be caused by a short to ground or voltage in the steering wheel module high and low circuits. |
| • | DTC B0026, an intermittent condition is likely to be caused by a poor connection at the steering wheel module connector or SDM. |
Step | Action | Yes | No |
|---|---|---|---|
|
Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section. Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section. Schematic Reference: SIR Schematics Connector End View Reference: SIR Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Is DTC B0022, B0024, or B0026 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 steering wheel module connector or replace the wiring. Is the repair complete? | Go to Step 11 | -- |
5 |
For all the above conditions, refer to Circuit Testing and Wiring Repairs . Did you find the condition? | Go to Step 10 | Go to Step 6 |
6 |
For all the above conditions, refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 11 | Go to Step 7 |
7 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you complete the replacement? | Go to Step 8 | -- |
8 |
Does the DTC reset? | Go to Step 9 | System OK |
9 | Replace the steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement . Did you complete the replacement? | Go to Step 11 | -- |
10 | Replace the steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement . Did you complete the replacement? | Go to Step 11 | -- |
11 |
Does the DTC reset? | Go to Step 2 | -- |
