B001B covers the deployment loop for the passenger seat belt anchor pretensioner, the unit that pulls at the anchor end of the belt beside the seat rather than at the retractor in the pillar. The sensing and diagnostic module measures that loop with the key on, and B001B is what it stores when the reading lands outside its window.
GM builds two pretensioners into most front seating positions. One works on the retractor and the other pulls the belt anchor down at the seat. Each one has a housing, an initiator and a canister of gas generating material, with its own deployment loop back to the SDM. In a collision of sufficient force the module sends current through the loop, the initiator lights the canister, and the gas produced pulls the slack out of the belt.
The symptom byte after the code is the part worth writing down. GM splits B001B into 01 for a short to battery, 02 for a short to ground, 04 for an open circuit, 0D for resistance above the threshold, and 0E for resistance below it. GM's guidance on bytes 04 and 0D is to check the circuit terminals for fretting and for a connector that is not seated correctly before any part gets replaced.
B001A is the same code for the driver side, and the two appear together often enough that GM covered both in the same service information.
Circuit report. The SDM is describing what it measures on the loop, and on a vehicle with no accident history that points at wiring and connectors around the seat.
On a vehicle that has been in a collision the same code can set because the pretensioner fired and left the loop open. That vehicle is also carrying deployment data in the module, and the belts themselves are locked and spent. Those are separate items on one repair order.
Not the loop fault. Wiring and a spent pretensioner are physical repairs, and the code returns on the next key cycle until they are done.
If the pretensioner fired, our seat belt pretensioner repair rebuilds the assembly so the belt works and the loop reads correctly again, and seat belt repair covers the buckle and retractor side of the same job. Once the hardware is right and the SDM is holding crash data, an airbag module reset clears that record from your original module.
B001B is GM SIR wording and shows up on Chevrolet, GMC, Buick and Cadillac vehicles equipped with anchor mounted pretensioners, along with the GM built Saab models of the same era. GM published preliminary information PIT4925A in February 2012 for the 2010 and 2011 Chevrolet Equinox and GMC Terrain covering an SIR light with B001A or B001B set with symptom code 02, 04, 0D or 0E, and it traces the concern to a shorted wire behind the plastic trim on the outboard side of the seat. Vehicles built without anchor pretensioners do not have this loop.
Read the code with its symptom byte before anything gets cleared. Those two digits decide whether you are looking for a break or a short, and they are gone once someone erases the code.
Then follow what GM published. Remove the plastic trim on the outboard side of the passenger seat and inspect the pretensioner harness for cuts and chafed wires, moving the seat through its full range while you look for a spot where the loom gets pinched or pulled. Repair the wire and reroute it away from whatever cut it. B0057 and B0058 cover the other passenger pretensioner deployment loop on the same vehicle, so read every stored code before deciding which unit is at fault.
Related codes: B001A, B0057, B0058
Keep reading:
Code scope: Chevrolet, GMC, Cadillac, Buick. The same number can mean something different on another manufacturer, so match the code to your make before you act on it.
A reset clears stored crash data. A replacement part fixes a hardware fault. We have read these codes since the nineties and will tell you which one you are looking at.
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