B1660 involves the passenger airbag active mode indicator, the lamp that tells occupants whether the passenger airbag is enabled. Its circuit is reading out of specification.
On vehicles with occupant detection, an indicator lamp shows whether the passenger airbag is currently on or off. The module drives that lamp and monitors the circuit to make sure it is working, because an indicator that cannot be trusted leaves occupants without accurate information. B1660 stores when the module reads that circuit as open, shorted, or otherwise out of range.
This one does not involve a firing loop or a sensor, which makes it different from most of the codes around it. The lamp is usually mounted in the center of the dash or on the console, and its wiring runs from the restraint module through the instrument panel harness. Dash work is the usual reason the circuit changes.
The module drives and measures this circuit live, so B1660 belongs with circuit faults and goes inactive when the lamp circuit reads correctly. Crash data is the permanent record kept after a deployment, and clearing codes with a scan tool has no effect on it.
Resetting the module does not repair the indicator circuit. As soon as the module powers up it tests the lamp again and stores B1660 if the circuit is still wrong. Check the lamp and its wiring first. Our reset service applies to Toyota and Lexus modules locked with crash data, which is a different problem from this one.
Toyota and Lexus both use B1660 for the passenger airbag active mode indicator. Vehicles that carry this code have occupant detection in the passenger seat, so check the seat system codes as well when this one appears.
Get to the indicator assembly and confirm the connector is seated and the lamp itself is good, because a failed bulb or LED assembly sets this code without anything else being wrong. Check for aftermarket wiring tapped into the dash harness. If the lamp and its wiring are sound, trace the circuit back toward the restraint module. Related codes: B1656, B1690, B1014.
Trace the wiring and connectors first. If the module still holds the fault after the repair, mail it to us and we will clear it.
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