B1BBB: Weight Sensor Inputs Shorted

Circuit fault

What B1BBB means

Each weight sensor under the passenger seat gets its own input line back to the occupant classification module, and the module depends on keeping those signals apart. B1BBB is written when it detects that inputs are connected to one another, which makes the individual corner readings meaningless even if every sensor is healthy.

A short between inputs almost always comes from the harness rather than the sensors. Wires bundled together, crushed in the same spot, or damaged by the same tool tend to fail together, and that is exactly the pattern this code describes. Checking the harness before testing individual sensors saves time, because the sensors themselves are rarely what joins two circuits.

Common causes

• Insulation worn through on bundled sensor wires where they cross the seat frame
• Harness crushed under a seat bolt or against the track during reinstallation
• A connector full of moisture bridging adjacent terminals
• Damage from an aftermarket install that cut into the seat harness bundle
• Terminals pushed out of position inside a connector body and touching

Crash data or hardware fault?

Shorted inputs are a live wiring condition, which puts B1BBB in the circuit family. Separate the wires and the fault is gone. Crash data, by contrast, is a permanent entry made at the moment airbags deploy, and it stays in module memory no matter how many times the codes are cleared.

Does our reset clear it?

A reset does nothing here, because the module tests those inputs constantly and finds the short again immediately. Repair the harness or the connector, confirm each sensor reads independently, then complete the occupant classification calibration. Our mail-in service is for airbag modules carrying deployment records or a stored internal fault.

Which makes throw it

Our lookup shows B1BBB on Chrysler, on passenger seats fitted with weight based occupant classification.

What to do next

Get the seat out or tipped back so you can see the full harness run, since a short between inputs is a visual find more often than a meter find. Look for a crush point at a seat bolt and for green corrosion inside the connectors. Check resistance between input pins with the sensors disconnected to confirm the short is in the wiring, then repair and recalibrate. Related codes: B1BBA, B1BBC, B0014.