B1B54: Passenger Belt Sensor, Low

Circuit fault

What B1B54 means

The passenger seat belt sensor lives in the buckle assembly and reports buckled or unbuckled to the restraint controller. The controller feeds that circuit and watches the voltage it sees. A low reading means the circuit is pulled closer to ground than either the buckled or unbuckled state should produce, so the controller flags the input as untrustworthy.

That signal feeds more than the reminder chime. It is one of the inputs used to decide how the passenger airbag and pretensioner should behave in a crash. With the sensor reading out of range, the controller loses part of the picture it uses for those decisions, and the airbag light stays on.

Common causes

• A failed switch inside the passenger seat belt buckle assembly
• The connector under the passenger seat unplugged or not fully latched
• Wiring under the seat pinched or cut by the seat track during adjustment
• A spilled drink or floor water reaching the buckle connector and corroding it
• Debris packed into the buckle holding the switch partly closed

Crash data or hardware fault?

This is a circuit code, which means the controller is reporting a measurement it is taking right now. Move the wire and the reading changes. Crash data behaves differently. It records a deployment that already happened, it is locked into module memory, and clearing codes at the vehicle has no effect on it.

Does our reset clear it?

A module reset will not correct a low seat belt sensor circuit, because the controller reads that input again as soon as power comes back and writes B1B54 a second time. The buckle, connector, or wiring has to be repaired first. Our mail-in service is the right tool when the module is holding crash data from a deployment, which is a separate condition entirely.

Which makes throw it

Chrysler is the make carrying B1B54 in our lookup, with the code tied to the first row passenger belt sensor circuit.

What to do next

Slide the passenger seat all the way forward and check the connector underneath it first, since seat track movement and floor spills account for most of these. Unplug and inspect the pins for green corrosion or a spread terminal. If the wiring is clean and the buckle switch still reads out of range, the buckle assembly is the part to replace, and we stock genuine OEM seat belt assemblies. Related codes: B1B33, B1B55, B1326.