Code Definition

B1891 — Airbag Tone Warning Indicator Circuit Short to Battery

System: Body  |  Type: Manufacturer-Specific  |  Make: Ford

About B1891

B1891 is a manufacturer-specific body diagnostic trouble code recorded for Ford vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1891 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

B1891 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Airbag Tone Warning Indicator is a Ford SRS feature that provides an audible warning to alert the driver of supplemental restraint system faults, particularly as a backup when the visual airbag warning lamp circuit itself has failed. The Restraints Control Module (RCM) drives a dedicated tone output (commonly through a sounder in the instrument cluster or a stand alone tone generator) and continuously monitors that output circuit for proper electrical behaviour. DTC B1891 sets when the RCM measures battery voltage on the tone driver circuit while it is commanding the output off, which the ...

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