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 B0077 : Left Front/Driver Side Impact Sensor (SIS) Performance
DTC B0078 : Right Front/Passenger Side Impact Sensor (SIS) Performance
DTC B0079 : Incorrect Left Front/Driver Side Impact Sensor (SIS) Installed
DTC B0080 : Discard Left Front/Driver Side Impact Sensor (SIS)
DTC B0081 : Incorrect Right Front/Passenger Side Impact Sensor (SIS) Installed
DTC B0082 : Discard Right Front/Passenger Side Impact Sensor (SIS)

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Side Impact Sensor Signal Left/Right | B0077, B0078 | B0077, B0078 | B0077, B0078 | B0077, B0078 | B0077, B0078

### Circuit/System Description

The inflatable restraint side impact sensor (SIS) utilizes a unidirectional 2-wire circuit. The SIS 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 SIS. When the ignition is turned on and input power from the SDM is first detected, the SIS 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 SIS continually communicates status messages to the SDM, which determines if a fault is present in the SIS circuit. When a fault is detected, the SDM resets the SIS 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

#### B0077 and B0078

• | A valid ID message is not received within 5 seconds of the SIS being powered up.

• | Status message is not received.

• | The SDM has failed twice to reset the SIS.

#### B0079 and B0081

• | The SDM has received an ID message from the SIS that does not match the ID stored in the SDM memory.

• | When two SIS resets are attempted without the correct identification being detected by the SDM.

#### B0080 and B0082

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

### 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 SIS.

### 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 connectors, inspect for damage or corrosion. Damage or corrosion in 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 side impact sensor.
2. Ignition ON, test for less than 1-volt between the side impact sensor voltage circuit terminal B and ground.

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

3. Ignition ON, test for less than 1-volt between the side impact sensor signal circuit terminal A and ground.

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

4. Test for infinite resistance between the side impact sensor voltage circuit terminal B and ground.

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

5. Test for less than 1 ohm between the side impact sensor voltage circuit terminals listed below:

• | Right side impact sensor terminal B and SDM harness connector terminal 8.

• | Left side impact sensor terminal B and SDM harness connector terminal 7.

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

6. Test for less than 1 ohm between the side impact sensor signal circuit terminals listed below:

• | Right side impact sensor terminal A and SDM harness connector terminal 29.

• | Left side impact sensor terminal A and SDM harness connector terminal 28.

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

7. If all circuits test normal, replace the appropriate side impact 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 Side Impact Sensor Replacement

• | SIR/SRS Wiring Repairs

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