Code Definition

P1875 — 4WD Low Switch circuit electrical

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

About P1875

P1875 is a manufacturer-specific powertrain diagnostic trouble code recorded for GM vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1875 is stored, the module has detected a signal or supply voltage lower than the expected operating range.

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.

P1875 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 4WD Low switch is a range position switch on the transfer case that tells the Transfer Case Control Module, or PCM on some GM applications, when the transfer case is in low range. The module uses this input to confirm range selection, adjust shift strategy, and illuminate the 4WD Low indicator. DTC P1875 sets when the module detects an electrical fault on the 4WD Low switch circuit, such as a missing signal, a short to ground or voltage, or a state that does not agree with the commanded or expected range. With this fault present the module may not confirm low range, the 4WD Low indicator m...

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