P1852

What it means

P1852 is a manufacturer-specific code. With the definition given here, it means the control unit has seen a short circuit to battery voltage on the 'B' circuit of the transfer case contact plate, which reports the selected transfer case range. The signal sits at battery voltage when it should be within the normal range for the selected position. The exact wiring and pin layout depend on the vehicle, so confirm the definition for the specific make and model.

Symptoms

• Warning light on, possibly for the four-wheel-drive system as well as the engine
• Four-wheel-drive range indicator flashing, wrong, or not displayed
• Transfer case will not shift between ranges, or the shift is refused
• Transfer case stays in a default mode, such as two-wheel drive or the last known range
• Transmission or transfer case behaving oddly, such as a limited shift strategy on some models

Possible causes

• Signal wire of the contact plate circuit chafed and shorted to a battery-voltage supply wirelikely
• Faulty transfer case contact plate (range position switch) with an internal short to supplylikely
• Corroded, wet or damaged connector at the transfer case or control module, allowing pins to bridgepossible
• Fault in the transfer case or transmission control module input circuit holding the signal highpossible
• Previous repair or aftermarket wiring (towing, lighting, accessories) wrongly spliced into the circuitpossible
• Harness damage near the transfer case from heat, road debris or off-road userare

How to diagnose

1. Read all stored codes and freeze frame data, and note whether other transfer case, transmission or communication codes are present
2. Check for any technical bulletins or known wiring faults for the specific model and engine
3. Visually inspect the harness and connectors at the transfer case and control module for chafing, melted insulation, water ingress, corrosion and bent or pushed-back pins
4. Check for signs of aftermarket wiring or past repairs near the circuit
5. With the ignition on and the contact plate unplugged, measure the voltage on the 'B' signal wire at the harness side; battery voltage there points to a wiring short or module fault
6. Check the contact plate's resistance or switch states across each range position against the manufacturer's specification
7. Wiggle-test the harness while watching live data for the range signal jumping to a high value
8. Isolate the circuit at the control module and test for continuity to supply wires to confirm a wiring short before condemning the module

How to fix

• Repair or replace the damaged section of wiring that is shorted to battery voltage, and secure and protect it from further chafing
• Replace the transfer case contact plate if its internal short is confirmed
• Clean, dry and repair or replace corroded or damaged connectors and terminals, and fix the source of water ingress
• Correct or remove faulty aftermarket or previous repair wiring, restoring the original circuit
• Replace or repair the control module only after the wiring and contact plate are proven good, and carry out any required programming or adaptation
• Clear the code after repair and test-drive, checking all ranges shift properly and the code does not return

Can I keep driving?

This code for other makes

• P1852BuickBrake Band Apply Solenoid Low Voltage
• P1852CadillacBrake Band Apply Solenoid Low Voltage
• P1852ChevroletBrake Band Apply Solenoid Low Voltage
• P1852GMBrake Band Apply Solenoid Low Voltage
• P1852GMCBrake Band Apply Solenoid Low Voltage
• P1852OldsmobileBrake Band Apply Solenoid Low Voltage
• P1852SaturnBrake Band Apply Solenoid Low Voltage
• P1852VolkswagenCAN Bus Unplausible Message From Engine Control

Nearby codes

• P1851OtherTransmission Transfer Case Contact Plate 'B' Open Circuit
• P1853OtherTransmission Transfer Case Contact Plate 'B' Short Circuit To Ground