Code Definition

P1891 — Transmission Transfer Case Contact Plate Ground Return Open Circuit

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

About P1891

P1891 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 P1891 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.

P1891 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 transfer case control module monitors transfer case shift position through a contact plate inside the electric shift encoder motor. The contact plate uses wipers riding on printed conductive tracks to report the selected range (2H, 4H, Neutral, 4L) back to the module, and it depends on a stable ground return for accurate position readings. DTC P1891 sets when the module detects that the ground return circuit for the contact plate is open, or the ground reference voltage is unstable beyond a calibrated threshold. With this code stored the module can lose track of the true transfer case posi...

Join TaT to view the complete code information and diagnostic details.

Quick Facts