B0104

DTC B0104

CIRCUIT DESCRIPTION
The inflatable restraint electronic frontal sensor (EFS) utilizes a unidirectional 2-wire circuit. The EFS modulates current on the interface to send ID, State of Health, and deployment commands to the inflatable restraint sensing and diagnostic module (SDM). The SDM serves as a power source and a ground for the EFS. When the ignition is turned on and input power from the SDM is first detected, the EFS responds by performing internal diagnostics and sending an ID to the SDM. The SDM considers the ID to be valid if the response time is less than 5 seconds. The EFS continually communicates status messages to the SDM, which determines if a fault is present in the EFS circuit. When a fault is detected, the SDM resets the EFS twice by removing and reapplying power. If the fault is still present, the SDM will set a diagnostic trouble code (DTC).

DTC DESCRIPTORS
This diagnostic procedure supports the following DTCs:
- DTC B0100 Electronic Front End Sensor 1 Performance
- DTC B0101 Discard Electronic Front End Sensor 1
- DTC B0102 Incorrect Electronic Front End Sensor 1 Installed
- DTC B0103 Electronic Front End Sensor 2 Performance
- DTC B0104 Discard Electronic Front End Sensor 2
- DTC B0105 Incorrect Electronic Front End Sensor 2 Installed

CONDITIONS FOR RUNNING THE DTC
Ignition 1 voltage is within the normal operating voltage range.

CONDITIONS FOR SETTING THE DTC
- DTC B0100 and B0103 will set when one of the following conditions occur:
- A valid ID message is not received within 5 seconds of the EFS being powered up.
- Status message is not received.
- The SDM has failed twice to reset the EFS.
- DTC B0102 and B0105 will set when one of the following conditions occur:
- The SDM has received an ID message from the EFS which does not match the ID stored in the SDM memory.
- When 2 EFS resets are attempted without the correct identification being detected by the SDM.
- DTC B0101and B0104 will set when the SDM has received 4 consecutive NOK (Not OK) messages from the EFS.

ACTION TAKEN WHEN THE DTC SETS
- The SDM commands the AIR BAG indicator ON via Class 2 serial data.
- The SDM attempts to reset the EFS.

CONDITIONS FOR CLEARING THE DTC
- 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.

DIAGNOSTIC AIDS
The following can cause an intermittent condition:
- A short between the EFS signal and voltage circuits
- High or low resistance in the EFS signal and voltage circuits
- Inspect the EFS signal and voltage circuits carefully for cutting and/or chafing
- Verify that the correct EFS is installed in the vehicle

TEST DESCRIPTION

Step 1 - Step 11:

Step 12 - Step 13:

The numbers below refer to the step numbers on the diagnostic table:
2. This step tests the communication status of the EFS.
6. This step tests for a short to ground, a high resistance, or an open in the EFS signal circuit.
7. This step tests for a short to ground, a high resistance, or an open in the EFS voltage circuit.
8. This step tests for a short to voltage in the EFS signal and voltage circuits.