Circuit Description
When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Then, the SDM provides input power to the electronic frontal sensor (EFS). When the input power is detected, the EFS responds by performing internal diagnostics. After that, the EFS sends an ID message to the SDM. The SDM will consider this to be a valid ID if the response time is less than 5 seconds after the EFS is powered up. The EFS will continually communicate a status message to the SDM. The SDM can reset the EFS by removing and applying power to it.
Conditions for Running the DTC
Ignition 1 voltage is within the normal operating voltage range.
Conditions for Setting the DTC
The DTC will set if one of the following conditions occur:
| • | A valid ID message is not received by the SDM within 5 seconds of the EFS being powered up |
| • | A status message is not received |
| • | The SDM has failed twice to reset the EFS |
Action Taken When the DTC Sets
The SDM commands the AIR BAG 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
Thoroughly inspect the wiring and connectors. An incomplete inspection of the wiring and the connectors may result in misdiagnosis, causing a part replacement with the reappearance of the malfunction.
The following are possible causes of the malfunction:
| • | A short between the EFS circuits |
| • | A short to ground, short to voltage, open, or high resistance in the EFS circuits. |
| • | The EFS connector |
| • | An internal EFS malfunction |
| • | The SDM connector |
| • | An internal SDM malfunction |
If an intermittent condition 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:
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Tests to see if the EFS connector is damaged or corroded.
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Tests to see if the EFS terminals are damaged or corroded.
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Tests to see if the SDM connector is damaged or corroded.
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Tests to see if the SDM terminals are damaged or corroded.
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Tests to see if there is a short between the 2 EFS circuits.
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Tests to see if there is an open or a high resistance in the 2 EFS circuits.
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Tests to see if there is a short to ground or a short to voltage in the 2 EFS circuits.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: SIR Schematics | |||
1 | Did you perform the Diagnostic System Check - SIR? | Go to Step 2 | |
Did you find and correct the condition? | Go to Step 12 | Go to Step 3 | |
Inspect the EFS terminals for damage or corrosion that may cause the malfunction. Do the EFS terminals exhibit signs of damage or corrosion? | Go to Step 9 | Go to Step 4 | |
Did you find and correct the condition? | Go to Step 12 | Go to Step 5 | |
Inspect the SDM terminals for damage or corrosion that may cause the malfunction. Do the SDM terminals exhibit any signs of damage or corrosion? | Go to Step 11 | Go to Step 6 | |
Test the EFS circuits for a short between the two circuits. Did you find and correct the condition? | Go to Step 12 | Go to Step 7 | |
Test the EFS circuits for an open or a high resistance. Did you find and correct the condition? | Go to Step 12 | Go to Step 8 | |
Test the EFS circuits for a short to ground or a short to voltage. Did you find and correct the condition? | Go to Step 12 | Go to Step 9 | |
9 | Replace the EFS. 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 |
