Normal Operation
The air bag Electronic Crash Sensor (ECS) module checks for correct ignition voltage by monitoring the voltage of circuit 950 (GN) at pin 2. If the ECS detects an ignition voltage below 9.0 volts on this pin, it will store a Diagnostic Trouble Code (DTC) B1318 in memory and flash a Lamp Fault Code (LFC) 12 (or higher priority code if one exists) on the air bag indicator.
Possible Causes
Voltage out of range at the ECS could be caused by:
an open in the ignition circuit that would prevent battery positive voltage (B+) from reaching the ECS pin 2.
a short to ground on the ignition feed circuit.
a concern in the charging system causing battery voltage to drop below 9.0 volts .
