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 in order to detect shorts to ground or a closed 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 ground. |
Conditions for Setting the DTC
Front end discriminating sensor signal terminal is less than or equal to 0.7 volts for 500 milliseconds.
Action Taken When the DTC Sets
The SDM commands ON the AIR BAG warning lamp 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 ground in the inflatable restraint front end discriminating sensor signal circuit. |
| • | Cutting or chafing of front end discriminating sensor signal 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:
-
Tests for a malfunctioning discriminating sensor.
-
Test for a short to ground in discriminating sensor signal circuit.
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 8 | -- |
Does the resistance measure greater than the specified value? | 950 ohms | Go to Step 6 | Go to Step 5 | |
5 | Replace the inflatable restraint front end discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Did you complete the replacement? | -- | Go to Step 8 | -- |
Does the resistance measure less than the specified value? | OL | Go to Step 7 | Go to Step 8 | |
7 | Locate and repair the short to ground in front end sensor signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 8 | -- |
8 |
Did you complete the action? | -- | Go to Step 2 | System OK |
