What does it mean?
P1849 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Transfer Case Contact Plate 'A' Short Circuit to Ground .
Symptoms
- Four-wheel drive mode will not change and the selector switch does nothing
- Mode indicator lamps flashing or all lit at once on the dash
- A service message for the four-wheel drive system on the cluster
- The vehicle stuck in one range, sometimes in neutral with no drive
- Check engine lamp on with drive-mode function reduced
Likely causes
- Water and road salt entering the transfer case shift motor and corroding the contact plate
- Worn or burnt tracks on the contact plate after long service
- Motor connector filled with moisture, bridging the A circuit to the case
- Underbody harness chafed against the frame, a heat shield or the driveshaft tunnel
- Failed encoder or motor assembly with an internal short
- Poor module or motor ground causing a misread state
- Module input circuit damaged by the ground short
How to fix it
- Read all codes from the transfer case module and note which contact plate circuits are affected
- Watch the contact plate state on the scan tool while commanding a mode change
- Unplug the shift motor connector and inspect for water, mud, salt and green corrosion
- Test the A circuit for a short to ground with the motor disconnected; if the short clears, the motor or encoder is at fault
- Check the underbody harness for chafe against the frame and shields
- Verify the motor supply and ground circuits and clean the ground stud
- Replace the encoder or shift motor assembly as required, then command each mode and confirm the plate states change correctly