Driveline Disconnect Switch Input Circuit


The PCM has detected a problem in the driveline disconnect switch input circuit. A code has been stored and the service engine light illuminated. A variety of different transfer case failure codes will trigger this code being stored in the PCM. Some models will also place the transmission in “limp in” mode along with this code being stored. Only all-wheel drive or four-wheel drive vehicles should exhibit this code. If this code is presented in a two-wheel drive vehicle, suspect a defective PCM or programming issue.

Code Set Parameters

In order for this code to be exhibited, the transfer case control system must detect an abnormal reading from one or more of its input/output speed sensors, the neutral sensor, or “LOW GEAR” sensor with the vehicle speed above 16 mph (most applications).


Symptoms can range from none at all to total transfer case failure (that results in a stranded motorist condition). Some of the most common symptoms may include service engine soon lamp illumination, harsh shifting, failure to shift (up or down), or engine stall when coming to a stop.

Common Causes

Common causes include defective input/output speed sensors, neutral sensors, or low gear sensors. Other causes include faulty solenoids and defective wiring harnesses and connectors. Driveshaft or universal joint failure may also contribute t this code being stored.

Common Misdiagnosis

Technicians report that many transfer cases are totally rebuilt (at great cost to the vehicle owner) or replaced when component replacement may repair the problem. Many repair facilities opt to totally rebuild or replace transfer cases instead of repairing them. This is a viable option, particularly in high-mileage vehicles, and also helps them to cover themselves from additional failures during the perceived warranty period.


  • A scanner (or code reader) and a digital volt/ohmmeter will be helpful when diagnosing this code. This type of code applies to all-wheel drive or four-wheel drive vehicles only
  • If this code is present in your two-wheel drive vehicle, suspect a faulty PCM or programming error. Begin your diagnosis with a visual inspection of all wiring and connectors
  • Repair or replace damaged, disconnected, shorted, or corroded wiring, connectors, and components as necessary
  • Always retest the system after repairs are completed to ensure success. If all system wiring, connectors, and components (Including fuses) appear to be in normal working order, connect the scanner (or code reader) to the diagnostic connector and record all stored codes and freeze frame data
  • This information can be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored
  • After the codes are cleared, operate the vehicle to see if the code returns
  • If the code fails to immediately return, you may have an intermittent condition
  • Intermittent conditions can prove to be quite a challenge to diagnose and in extreme cases may have to be allowed to worsen before a correct diagnosis can be made
  • If the code immediately returns, check for battery voltage on the input side of the input/output speed sensors, neutral sensors, or low gear sensors using the digital volt/ohmmeter
  • If there is no voltage present on the input side of the switch, disconnect any related control modules and check for continuity between the system fuse and the input circuit at the clutch position sensor
  • Repair open or shorted circuits as required
  • If voltage is present on the input side of the input/output speed sensors, neutral sensors, or low gear sensors and none on the output side suspect a faulty input/output speed sensors, neutral sensors, or low gear sensors
  • Adjust or replace the switch as needed and retest the system afterward to ensure a successful repair. If there is voltage present on the output circuit of the input/output speed sensors, neutral sensors, or low gear sensors, check circuit continuity and resistance between the switch and the PCM
  • Take care to disconnect all related control modules before testing
  • Again, refer to the vehicle wiring diagram to ensure that all circuits are tested
  • Repair or replace system open or shorted circuits/connectors as required
  • If all circuits coincide with manufacturer’s specifications, suspect a defective PCM
  • Remember that PCM failure is rare and replacement will require reprogramming