P1885

What Does Code P1885 Mean?

DTC P1885 indicates that the Powertrain Control Module (PCM) or Transfer Case Control Module (TCCM) has detected a short circuit to ground in the electrical circuit for the Transfer Case Disengaged Solenoid. This solenoid is a crucial component within the transfer case system, responsible for electrically engaging or disengaging the transfer case clutch or shift forks, allowing the vehicle to transition between different drive modes such as two-wheel drive (2WD), four-wheel drive high (4WD-HIGH), four-wheel drive low (4WD-LOW), or a neutral position. When a short to ground occurs, it means there is an unintended path for electrical current to flow directly from the solenoid’s control circuit to the vehicle’s chassis or another grounded component, bypassing the solenoid coil. This results in an abnormally low voltage reading or excessively high current draw on the circuit as monitored by the control module, outside of its calibrated operating parameters. The module interprets this anomaly as a fault, illuminating the Malfunction Indicator Lamp (MIL) and setting code P1885, signifying that it cannot effectively control the solenoid and consequently, the transfer case’s engagement state.

Common Symptoms

• Malfunction Indicator Lamp (MIL) illumination: The “Check Engine” light or a dedicated “Service 4WD” warning lamp will typically illuminate.
• Inability to select or deselect 4WD modes: The vehicle may be stuck in 2WD, stuck in 4WD, or unable to shift into low range or neutral, depending on the solenoid’s function and the specific short.
• Erratic or intermittent 4WD system operation: The 4WD system may engage or disengage unexpectedly, or fail to respond to driver input.
• Warning messages: Dashboard messages such as “Service 4WD System” or similar alerts may appear.
• Driveline binding or noise: If the transfer case is partially engaged or disengaged incorrectly, symptoms like driveline binding during turns or unusual noises from the transfer case area may occur, particularly if operating on a high-traction surface while the transfer case is locked.

What Causes the Code P1885?

• Damaged Wiring Harness: The most common cause is physical damage to the wiring harness leading to the transfer case disengaged solenoid. This includes chafed insulation, melted wires, or wires that have been pinched and are now making contact with the vehicle’s frame, engine block, or another ground source.
• Faulty Transfer Case Disengaged Solenoid: The solenoid itself can develop an internal short circuit. This could be due to insulation breakdown within the coil windings, moisture intrusion, or physical damage to the solenoid body or its integrated connector.
• Corroded Electrical Connectors: Moisture, road salt, or debris can enter the electrical connector for the solenoid, leading to corrosion on the terminals. This corrosion can create an unintended conductive path, effectively shorting the circuit to ground.
• Faulty Transfer Case Control Module (TCCM) or Powertrain Control Module (PCM): While less common, an internal short within the control module’s driver circuit for the transfer case solenoid can also trigger this code. This would typically be considered after ruling out all external wiring and solenoid issues.

How to Diagnose and Troubleshoot

Diagnosing P1885 requires systematic electrical testing and visual inspection. Always begin by gathering freeze frame data and any other related DTCs using an OBD-II scanner.

1. Retrieve Diagnostic Trouble Codes (DTCs): Connect an OBD-II scan tool and retrieve all active and pending DTCs. Note any freeze frame data, as this provides conditions under which the code was set. Clear the codes and see if P1885 immediately resets.
2. Visual Inspection of Wiring and Connectors:
   • Locate the transfer case disengaged solenoid. This often requires lifting the vehicle.
   • Carefully inspect the electrical connector at the solenoid for signs of corrosion, bent pins, or loose connections.
   • Trace the wiring harness from the solenoid back to the TCCM/PCM. Look for any visible signs of damage, such as chafing, cuts, melting, or pinching. Pay close attention to areas where the harness passes through firewalls, over sharp edges, or near exhaust components.
3. Electrical Testing of Solenoid Circuit (Using a Digital Multimeter – DMM):
   • Disconnect the Solenoid: With the ignition OFF, disconnect the electrical connector from the transfer case disengaged solenoid.
   • Test Wiring Harness for Short to Ground:
     1. Set your DMM to the resistance (Ohms) scale.
     2. Identify the control circuit wire from the TCCM/PCM at the harness side of the disconnected connector (consult a wiring diagram for pin identification).
     3. Place one DMM lead on the control circuit wire terminal at the harness connector and the other DMM lead on a known good chassis ground (e.g., a clean, unpainted metal part of the vehicle frame).
     4. A reading close to 0 Ohms or very low resistance indicates a direct short to ground in the wiring harness. If the reading is high (thousands of Ohms or open circuit), the harness is likely okay in terms of a direct short to ground.
   • Test Solenoid for Internal Short to Ground:
     1. With the solenoid still disconnected from the harness, place one DMM lead on each terminal of the solenoid itself (if accessible, or on the solenoid’s connector terminals).
     2. Then, place one DMM lead on one solenoid terminal and the other lead on the metal body of the solenoid (if applicable) or a known good ground point near the solenoid.
     3. A reading close to 0 Ohms indicates an internal short to ground within the solenoid itself.
     4. Also, measure the resistance across the two solenoid terminals (if it’s a two-wire solenoid). Compare this reading to factory specifications (typically in the range of 10-40 Ohms). An open circuit (OL on DMM) indicates an open winding, while a reading significantly lower than specified could indicate a partial short or damaged winding.
   • Check for Power and Ground at Harness (Key On Engine Off – KOEO):
     1. Refer to the vehicle’s wiring diagram to determine the expected power and ground signals at the solenoid connector with the ignition ON (KOEO).
     2. With the DMM set to Volts DC, probe the power supply wire at the harness connector (if present) and a known good ground. Verify battery voltage.
     3. Probe the control wire and measure its voltage. A short to ground will typically pull this voltage down to near 0V or significantly lower than expected when the module attempts to activate the circuit.
4. Wiggle Test: If no obvious short is found, connect the DMM to monitor resistance or voltage on the suspect circuit. Gently wiggle, flex, and pull on the wiring harness, especially at common stress points and connectors, while observing the DMM for any sudden fluctuations or changes in reading. This can help identify intermittent shorts or poor connections.

Recommended Repairs and Solutions

Once the root cause of P1885 has been accurately identified through diagnosis, the appropriate repair can be performed.

• Repair or Replace Damaged Wiring: If the wiring harness is found to be shorted to ground, the damaged section must be meticulously repaired. This involves cutting out the compromised section, soldering in new wire of the correct gauge and insulation type, and sealing the repair with heat-shrink tubing to prevent future corrosion and re-shorting. For extensive damage, replacing the entire sub-harness may be more efficient and reliable. Ensure proper routing and securing of the harness away from hot or moving components.
• Replace Faulty Transfer Case Disengaged Solenoid: If the solenoid itself exhibits an internal short circuit or incorrect resistance, it must be replaced. Always use an OEM-equivalent part to ensure proper fitment, electrical characteristics, and long-term reliability. After replacement, ensure the electrical connector is clean, dry, and securely fastened.
• Clean and Repair Corroded Connectors: If corrosion is present in the solenoid’s electrical connector, thoroughly clean the terminals using a specialized electrical contact cleaner and a small wire brush or pick. Ensure all traces of corrosion are removed. Apply a thin layer of dielectric grease to the terminals before reconnecting to help prevent future moisture intrusion and corrosion. If terminals are severely corroded or damaged, connector replacement may be necessary.
• Transfer Case Control Module (TCCM) / Powertrain Control Module (PCM) Replacement: This is a last resort and should only be considered after all other potential causes (wiring, solenoid) have been thoroughly ruled out. If the control module is determined to be the cause, it will need to be replaced and typically programmed to the vehicle using specialized diagnostic equipment.
• Post-Repair Verification: After completing any repairs, clear the DTCs from the PCM/TCCM. Perform a comprehensive test drive, cycling through all available 4WD modes multiple times, to ensure the code does not return and the transfer case system operates as intended. Monitor real-time data for the solenoid circuit if accessible via the scan tool to confirm proper operation.