B1C2B: Right Thorax Airbag Circuit Low

Circuit fault

What B1C2B means

Thorax airbags protect the chest in a side impact and are packed into the outboard bolster of the seat back. The controller sends a small current through the squib and measures resistance. A low reading means more current is getting through than it should, which points toward two conductors touching or a squib that has partly shorted internally.

Seat mounted circuits give this complaint more than most. Wiring under a seat flexes through every adjustment, sits near metal rails, and passes through a connector that gets stepped on and rained on through an open door. A low reading is often intermittent at first, showing up only when the seat is in a particular position.

Common causes

• Insulation worn through where the seat harness rubs the seat frame or rail
• A shorted squib inside the right seat thorax airbag
• Corrosion bridging terminals in the connector under the passenger seat
• A pinched wire from seat removal or aftermarket seat cover installation
• Moisture in the connector from a spill or a leaking door seal

Crash data or hardware fault?

The controller is taking a live resistance measurement, so B1C2B is a circuit fault. It goes inactive on its own once the reading comes back into range. Crash data is the category that does not move: written at deployment, kept in the controller, and removed only by resetting the unit.

Does our reset clear it?

Clearing B1C2B while the short is still present accomplishes nothing. The controller checks the thorax loop constantly and the code returns immediately. Repair the harness or replace the airbag first. The mail-in reset is for controllers that are locked with deployment data, and it is the right step once the vehicle side of the repair is done.

Which makes throw it

Jeep reports B1C2B for the right seat thorax squib. Left side thorax circuits carry their own numbers, so the code is already telling you which seat to work on.

What to do next

Slide the passenger seat all the way back and inspect the harness where it runs along the rail, since a rub through is the usual cause of a low reading here. Disconnect the airbag and measure from the controller side to separate the harness from the module. If the squib itself reads low, the seat side airbag needs replacing, and we stock genuine OEM units. Related codes: B1C27, B1C38, B1811.