B0101

DTC B0100, B0101, B0102, B0103, B0104, or B0105

Circuit Description

The inflatable restraint front end sensor utilizes a unidirectional 2-wire circuit. The front end sensor 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 front end sensor. When the ignition is turned on and input power from the SDM is first detected, the front end sensor 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 front end sensor continually communicates status messages to the SDM, which determines if a fault is present in the front end sensor circuit. When a fault is detected, the SDM resets the front end sensor twice by removing and reapplying power. If the fault is still present, the SDM will set a diagnostic trouble code (DTC).

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 front end sensor being powered up.
- Status message is not received.
- The SDM has failed twice to reset the front end sensor.
- DTC B0102 and B0105 will set when one of the following conditions occur:
- The SDM has received an ID message from the front end sensor which does not match the ID stored in the SDM memory.
- When two front end sensor resets are attempted without the correct identification being detected by the SDM.
- DTC B0101 and B0104 will set when the SDM has received 4 consecutive NOK (Not OK) messages from the front end sensor.

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 front end sensor.

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 front end sensor signal and low reference circuits
- High or low resistance in the front end sensor signal and low reference circuits
- Inspect the front end sensor signal and low reference circuits carefully for cutting and/or chafing
- Verify that the correct front end sensor is installed in the vehicle

Refer to Testing for Intermittent Conditions and Poor Connections, Testing For Intermittent and Poor Connections

Test Description

The numbers below refer to the step numbers on the diagnostic table:

2. Tests the communication status of the front end sensor.
6. Tests for a short to ground, a high resistance, or an open in the front end sensor signal circuit.
7. Tests for a short to ground, a high resistance, or an open in the front end sensor low reference circuit.
8. Tests for a short to voltage in the front end sensor signal and low reference circuits.