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 Circuit 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 commands the AIR BAG indicator ON via class 2 serial data.

• | The SDM attempts to reset the SIS.

### Conditions for Clearing the DTC

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

• | You issue a scan tool CLEAR DTC 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 SIS signal and voltage circuits

• | High or low resistance in the SIS signal and voltage circuits

• | Inspect the SIS signal and voltage circuits carefully for cutting and/or chafing.

• | Verify that the correct SIS is installed in the vehicle.

### Reference Information

#### Schematic Reference

SIR Schematics

#### Connector End View Reference

SIR Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Testing

1. With the ignition ON, use a scan tool to observe the SIR DTC display. Verify DTC B0079, B0080, B0081, or B0082 are current.

⇒ | If DTC B0079, B0080, B0081, or B0082 are current, replace the malfunctioning SIS.

• | For DTCs B0079 and B0080 replace the left SIS.

• | For DTCs B0081 and B0082 replace the right SIS.

2. With the ignition ON, use a scan tool to observe the SIR DTC display. Verify DTC B0077 or B0078 are current.

⇒ | Inspect and test wiring system components.

• | For DTC B0077 replace the left SIS.

• | For DTC B0078 replace the right SIS.

3. Verify DTC B0077, B0078, B0079, B0080, B0081, or B0082 are not current.
4. If DTC B0077, B0078, B0079, B0080, B0081, or B0082 reset as current, remove the SDM connector. Inspect the SDM connector for damage or corrosion that may cause a malfunction in the SIS circuits.

⇒ | If damage or corrosion is found make the appropriate repair.

⇒ | 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