For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

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

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Front Impact Sensor Signal Left/Right | B0100, B0103 | B0100, B0103 | B0100, B0103 | B0100, B0103 | B0100, B0103
Front End Sensor Low Reference Left/Right | -- | B0100, B0103 | B0100, B0103 | -- | B0100, B0103

### Circuit/System 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 (SOH), 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 will respond 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).

### Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

### Conditions for Setting the DTC

#### B0100 and B0103

• | 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.

#### B0102 and B0105

• | The SDM has received an ID message from the EFS that 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.

#### B0101 and B0104

Will set when the SDM has received a NOK (Not OK) message from the EFS.

### Action Taken When the DTC Sets

• | The SDM requests the instrument panel cluster (IPC) to illuminate the AIR BAG indicator.

• | The SDM attempts to reset the EFS.

### Conditions for Clearing the DTC

• | The condition for setting the DTC no longer exists.

• | A history DTC will clear once 100 malfunction-free ignition cycles have occurred.

### Reference Information

#### Schematic Reference

SIR Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

SIR System Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

Important: Refer to SIR Service Precautions.

When removing the connectors, inspect for damage or corrosion. Damage or corrosion to the following requires repair or replacement of the affected component/connector:

• | Front end sensor

• | SDM module

• | Front end sensor wiring harness connector

• | SDM wiring harness connector

1. Ignition OFF, disconnect the harness connector at the SDM and the appropriate front end sensor.
2. Ignition ON, test for less than 1-volt between the front end sensor signal circuit terminal B and ground.

⇒ | If greater than the specified range, test the circuit for a short to voltage.

3. Ignition ON, test for less than 1-volt between the front end sensor low reference circuit terminal A and ground.

⇒ | If greater than the specified range, test the circuit for a short to voltage.

4. Test for infinite resistance between the front end sensor signal circuit terminal B and ground.

⇒ | If less than the specified value, test the circuit for a short to ground.

5. Test for less than 1 ohm between the front end sensor signal circuit terminals listed below:

• | Right front end sensor terminal B and SDM harness connector terminal 6.

• | Left front end sensor terminal B and SDM harness connector terminal 5.

⇒ | If greater than the specified range, test the signal circuit for an open/high resistance.

6. Test for less than 1 ohm between the front end low reference circuit terminals listed below:

• | Right front end sensor terminal A and SDM harness connector terminal 27.

• | Left front end sensor terminal A and SDM harness connector terminal 26.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance.

7. If all circuits test normal, replace the appropriate front end sensor.
8. Reconnect all SIR components. Ignition ON, verify the DTC does not set as current.

⇒ | If the DTC resets as current , replace the SDM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Inflatable Restraint Front End Sensor Replacement

• | SIR/SRS Wiring Repairs

• | Control Module References for SDM replacement, setup, and programming