Code Definition

P1804 — 4WD high indicator circuit open or shorted to ground

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

About P1804

P1804 is a manufacturer-specific powertrain diagnostic trouble code recorded for Ford vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1804 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit; a short-circuit (voltage pulled to ground or to supply) in the monitored circuit; and a signal or supply voltage higher 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.

P1804 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 sets when the powertrain control module (PCM) or 4WD control module detects an open or a short to ground in the 4WD high indicator lamp circuit. The module monitors the voltage of the indicator circuit, and if the signal is out of the expected range for a calibrated duration, either from no continuity (open) or a short to ground, the fault code is triggered. This affects proper illumination of the 4WD high indicator in the instrument cluster, which reflects the transfer case status. The driver may see the 4WD high indicator fail to light, stay on, or behave inconsistently with the sel...

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