B0101

CIRCUIT DESCRIPTION
The inflatable restraint electronic frontal sensor (EFS)- Left, also known as inflatable restraint front end discriminating sensor, loop is a 2 wire 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 EFS-Left. When input power is first detected, the EFS-Left responds by performing internal diagnostics. Next the EFS-Left 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-Left is powered up. The EFS-Left will continually communicate a status message to the SDM. The SDM can reset the EFS-Left by removing and applying power to it.

CONDITIONS FOR RUNNING THE DTC
^ Ignition 1 Voltage is within the normal operating voltage range.
^ EFS-Left loop is not shorted to voltage.
^ EFS-Left loop is not shorted to ground.

The SDM monitors the EFS-Left loop with the power on.

CONDITIONS FOR SETTING THE DTC
^ The SDM has detected one of the following conditions due to a fault in the EFS-Left interface circuit:
- A valid ID message is not received within 5 seconds of the EFS-Left being powered up.
- Status message is not received.
^ The SDM has failed twice to reset the EFS-Left.

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 in the EFS-Left circuit:
^ A short to ground or short to voltage in the EFS-Left circuit
^ High or low resistance
^ Inspect the EFS-Left signal and ground circuits carefully for cutting and/or chafing

If any of the above conditions are found refer to Testing for Intermittent and Poor Connections in Diagnostic Aids.

TEST DESCRIPTION

Steps 1-2:

Steps 3-12:

The numbers below refer to the step numbers on the diagnostic table.
6. This step tests the EFS-Left signal and EFS-Left ground circuits for an open or high resistance.
7. This step tests between the EFS-Left signal and EFS-Left ground circuits for resistance.
8. This step tests the EFS-Left signal and EFS-Left ground circuits for a short to voltage.