Circuit Description
Important: This DTC is also used for the inflatable restraint electronic frontal sensor (EFS) found on the 35/36 series trucks. The 35/36 series trucks have one EFS located at the front of the vehicle. The EFS is diagnosed the same way as the inflatable restraint side impact sensor (SIS) used on Utility models. The following diagnostics will refer to the left SIS or the EFS depending on what series truck you are diagnosing.
The SIS/EFS circuit consists of a SIS/EFS, the SIS/EFS signal circuit, and the SIS/EFS voltage circuit. When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM provides input power to the SIS/EFS. When input power is first detected, the SIS/EFS responds by performing internal diagnostics. The SIS/EFS then 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 SIS/EFS is powered up. The SIS/EFS will continually communicate a status message to the SDM. The SDM is capable of resetting the SIS/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 SDM has received an ID message from the left SIS/EFS which does not match the ID stored in the SDM memory. |
| • | When two left SIS/EFS resets are attempted without the correct identification being detected by the SDM. |
Action Taken When the DTC Sets
| • | The SDM commands ON the AIR BAG indicator via Class 2 serial data. |
| • | The SDM attempts to reset the left SIS/EFS. |
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists. |
| • | You can issue a scan tool CLEAR DTCs command. |
| • | A history DTC will clear once 255 malfunction free ignition cycles have occurred. |
Diagnostic Aids
Verify that the proper left SIS/EFS is installed in the vehicle.
Test Description
The following number refers to the step number in the diagnostic table:
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: SIR Schematics | |||
1 | Did you perform A Diagnostic System Check - SIR? | Go to Step 2 | |
Does the scan tool indicate that DTC B0079 is current? | Go to Step 3 | Go to Diagnostic Aids | |
3 | Replace the left SIS/EFS. Refer to Inflatable Restraint Side Impact Sensor Replacement or Inflatable Restraint Front End Discriminating Sensor Replacement . Did you complete the replacement? | Go to Step 4 | -- |
4 |
Did you complete the repair? | -- | |
