Circuit Description
When you first turn ON the ignition, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Then the SDM proceeds to continuous monitoring. The SDM contains a resistor network connected to 5 volts, ground, and to the SDM front end sensor feed. The 1.0 K ohms resistor in the inflatable restraint front end discriminating sensor parallel to the normally open switch provides a parallel path to ground. This causes a specified percentage of voltage in order to appear at the SDM front end sensor feed input. The SDM monitors this voltage to detect a short to voltage or an open discriminating sensor.
Conditions for Running the DTC
| • | The SDM is configured for an inflatable restraint front end discriminating sensor. |
| • | Ignition 1 Voltage is within the normal operating voltage range. |
| • | Front end discriminating sensor signal circuit is not shorted to voltage. |
Conditions for Setting the DTC
Front end discriminating sensor signal circuit is more than 3.4 volts for 500 milliseconds.
Action Taken When the DTC Sets
The SDM commands the AIR BAG warning indicator ON via Class 2 serial data.
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used. |
| • | A history DTC will clear once 255 malfunction free ignition cycles have occurred. |
Diagnostic Aids
The following can cause an intermittent condition:
| • | A short to voltage in the front end discriminating sensor signal circuit. |
| • | Cutting or chafing of front end discriminating sensor signal and/or ground circuit. |
Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: SIR Schematics | ||||
1 | Did you perform A Diagnostic System Check - SIR? | -- | Go to Step 2 | |
2 |
Did you find and correct the condition? | -- | Go to Step 3 | Go to Step 4 |
3 |
Did you complete the repair? | -- | Go to Step 11 | -- |
Does the resistance measure greater than the specified value? | 1050 ohms | Go to Step 5 | Go to Step 6 | |
5 | Replace the discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
6 | Test the resistance between the discriminating sensor ground circuit and a known good ground. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 |
7 |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 |
8 |
Does the voltage measure less than the specified value? | 1 V | Go to Step 11 | Go to Step 9 |
9 |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
10 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
