For 1990-2009 cars

## DTC B0077 Coupe

### Circuit Description

When the ignition is turned ON, the SDM performs a self-test to diagnose malfunctions inside the module. The SDM provides input power to the SIS. When input power is first detected, the SIS responds by performing internal diagnostics. Next the SIS sends an ID message to the SDM. The SDM will consider this to be a valid ID if the response time is less than 5 seconds after the SIS is powered up. The SIS will continually communicate a status message to the SDM. The SDM can reset the SIS by removing and applying power to it.

### DTC Parameters

DTC B0077 can be set when the left SIS malfunctions. The following conditions must be met to set this DTC:

• | Ignition voltage is present at the SDM continuous.

• | The SDM detects a left SIS fault.

• | The SDM resets the left SIS twice without detecting correct operation.

### Action Taken

• | DTC B0077 will set.

• | The air bag telltale will be ON.

### Diagnostic Aids

• | When attempting to diagnose an intermittent passenger loop fault, use the scan tool to monitor current DTCs. Wiggle wires and check connections while watching for a current DTC to appear and/or disappear on the scan tool.

• | Always start diagnosis of SIR DTCs with an inspection of wiring and SIR components for visible damage.

• | A short to ground in circuits 2131 or 2132 could cause this DTC.

• | A short between circuits 2131 or 2132 and another vehicle circuit could cause this DTC.

• | Always perform the Diagnostic System Check - SIR procedure before using this chart.

## DTC B0077 Sedan

### Circuit Description

When the ignition is turned On, the SDM performs a self-test to diagnose malfunctions inside the module. The SDM provides input power to the SIS. When input power is first detected, the SIS responds by performing internal diagnostics. Next the SIS sends an ID message to the SDM. The SDM will consider this to be a valid ID if the response time is less than 5 seconds after the SIS is powered up. The SIS will continually communicate a status message to the SDM. The SDM can reset the SIS by removing and applying power to it.

### DTC Parameters

DTC B0077 can be set when the left SIS malfunctions. The following conditions must be met to set this DTC:

• | Ignition voltage is present at the SDM continuous.

• | The SDM detects a left SIS fault.

• | The SDM resets the left SIS twice without detecting correct operation.

### Action Taken

• | DTC B0077 will set.

• | The air bag telltale will be ON.

### Diagnostic Aids

• | When attempting to diagnose an intermittent passenger loop fault, use the scan tool to monitor current DTCs. Wiggle wires and check connections while watching for a current DTC to appear and/or disappear on the scan tool.

• | Always start diagnosis of SIR DTCs with an inspection of wiring and SIR components for visible damage.

• | A short to ground in circuits 2131 or 2132 could cause this DTC.

• | A short between circuits 2131 or 2132 and another vehicle circuit could cause this DTC.

• | Always perform the Diagnostic System Check - SIR procedure before using this chart.