The inflatable restraint sensing and diagnostic module (SDM) monitors the inflatable restraint front end discriminating sensor circuit for front impact detection. The SDM processes the signal provided by the front end discriminating sensor to further support deployment of the air bags. The front end discriminating sensor is an input only to the SDM and does not directly cause air bag deployment. When the ignition is turned ON, the SDM performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored.
Ignition 1 voltage is within the normal operating voltage range.
The SDM detects the voltage at the front end discriminating sensor signal is greater than 3.65 volts for 500 milliseconds.
The SDM commands ON the AIR BAG indicator via Class 2 serial data.
• | The condition responsible for setting the DTC no longer exists. |
• | You issue a scan tool CLEAR DTCs command. |
• | A history DTC will clear once 255 malfunction free ignition cycles have occurred. |
A broken or chafed wire in the front end discriminating sensor circuit may cause an intermittent condition to occur. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
The numbers below refer to the step numbers on the diagnostic table:
Tests for a malfunctioning front end discriminating sensor.
Tests for an open or high resistance in the front end discriminating sensor signal circuit.
Tests for an open or high resistance in the front end discriminating sensor reference low circuit.
Tests for a short to voltage in the front end discriminating sensor signal circuit.
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
Schematic Reference: SIR Schematics | ||||
1 | Did you perform the Diagnostic System Check - SIR? | -- | Go to Step 2 | |
2 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 3 |
3 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 4 |
4 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 5 |
Does the resistance measure more than the specified value? | 1050 ohms | Go to Step 9 | Go to Step 6 | |
Test the front end discriminating sensor signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 | |
Test the front end discriminating sensor reference low circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 | |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | |
9 | Replace the front end discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Did you complete the replacement? | -- | Go to Step 10 | |
10 |
Does the DTC reset? | -- | Go to Step 11 | System OK |
11 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK |