Code Definition

P1842 — Transmission Transfer Case Differential Lock-Up Feedback Switch Circuit Failure

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

About P1842

P1842 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 P1842 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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.

P1842 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 relates to the differential lock feedback switch in the transfer case, which confirms to the control module whether the differential lock is actually engaged or disengaged. The control module expects specific voltage signals from this switch to match the commanded lock state. DTC P1842 sets when the feedback signal is inconsistent, out of range, or does not transition as expected during operation or a self check. When this code is present the system may not confirm a lock request, could disable the differential lock feature, and will usually illuminate a warning light.

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