B1BBA: Weight Sensor Supply Circuit Fault

Circuit fault

What B1BBA means

The weight sensors under the passenger seat do not generate power on their own. The occupant classification module supplies them with a reference voltage and reads the signals that come back. B1BBA sets when that supply line is out of range, shorted, or missing, which takes out the entire set of sensors at once.

Seeing this code alongside several sensor input faults is normal and worth noting. A single failed supply wire makes every corner of the seat look wrong, so chasing four bad sensors would waste a lot of time when one shared circuit is the actual problem.

Common causes

• The supply wire shorted to ground in the seat harness
• The supply wire shorted to battery voltage from a chafe or a bad accessory tap
• A broken supply conductor at a flex point where the harness enters the seat
• A corroded or backed out pin at the module connector carrying the supply
• A failed sensor pulling the shared supply line down for the whole group

Crash data or hardware fault?

B1BBA describes a live electrical condition, so it sits with the circuit codes. Repair the supply and the reading corrects itself on the next check. Crash data is stored history, written into the airbag module when a deployment occurs, and no scan tool or code clear removes it from memory.

Does our reset clear it?

Clearing codes or resetting a module will not restore a failed supply circuit. The occupant classification module energizes that line every key cycle, finds the same fault, and records B1BBA again. Fix the wiring or the sensor causing the short, then recalibrate the system. Mail-in resets address modules with crash data or stored internal faults.

Which makes throw it

Chrysler is the make listed for B1BBA, on passenger seats that use weight sensors for occupant classification.

What to do next

Unplug the weight sensors one at a time with the module connected and watch whether the supply reading recovers, since that isolates a single shorted sensor from a shorted wire quickly. If the supply stays out of range with everything unplugged, the fault is in the harness or the module. Repair what you find, then run the occupant classification calibration. Related codes: B1BAA, B1BBB, B1493.