What does it mean?
P1853 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Transfer Case Contact Plate 'B' Short Circuit to Ground .
Symptoms
- Four-wheel drive will not shift between modes and the switch appears dead
- Dash mode lamps flashing, cycling or displaying more than one mode at once
- Service four-wheel drive message on the cluster
- Drive lost in one or more ranges, occasionally leaving the vehicle in neutral
- Check engine lamp on with reduced system function
Likely causes
- Moisture and road salt inside the transfer case shift motor corroding the plate and its contacts
- Contact plate tracks worn or burnt after repeated mode changes
- Water in the motor connector bridging the B circuit to the case
- Underbody harness rubbed through against the frame rail, a bracket or a heat shield
- Encoder or motor assembly with an internal short to its housing
- Corroded ground point for the transfer case module
- Module input circuit damaged after the short
How to fix it
- Read the transfer case module codes and note which plate circuits are involved
- Command each mode with the scan tool and log the contact plate states as they change
- Disconnect the shift motor and check whether the short to ground on circuit B disappears
- Inspect the motor connector for water, mud, salt and corroded pins, and dry it before retesting
- Follow the harness under the vehicle and look for chafe at frame rails, brackets and shields
- Check the module supply and ground circuits and clean any corroded ground
- Replace the encoder or the shift motor assembly, then verify every mode change and the plate states