Code Definition

P1843 — Transmission Transfer Case Differential Lock-Up Feedback Switch Open Circuit

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Generic

About P1843

P1843 is a manufacturer-specific powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1843 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1843 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

This DTC is specific to an open circuit in the differential lock feedback switch circuit of the transfer case. The switch confirms the actual position of the differential lock mechanism to the control module. During operation or a system self check, the module monitors the feedback signal and expects a voltage change matching the switch state. DTC P1843 sets when no signal is received, indicating a break in the wiring, the connector, or the switch contacts. The system may then be unable to confirm the lock position, disable the lock feature, and illuminate a warning light.

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