What it means
General electrical fault on the 4WD selector switch input — used by the operator to engage 4WD on demand (4H, 4L, Auto). With the input invalid the transfer case cannot honour operator selection.
At a glance
- Usually lights the check-engine light
How it works
The 4WD selector switch tells the transfer-case control system which drive mode the driver has selected. This code sets when the switch input circuit has an electrical fault, so the control system may not receive a valid selection for 4H, 4L, or Auto.
Common causes
Most likely first.
- Faulty 4WD selector switch
- Open or short in the switch wiring
- Loose, damaged, or corroded connector
- Fault in the transfer case control circuit
- Fault in the control module
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Record freeze-frame data and check scan-tool 4WD selector status while moving the selector through its available positions.
- Inspect the selector switch, its connector, and nearby wiring for damage, loose fit, corrosion, or water intrusion.
- Check whether the transfer case responds to any selector position and note warning messages or other 4WD-related codes.
- Using the wiring diagram, test the switch circuit for an open, short, or poor connection, following the manufacturer's circuit-isolation procedure.
- If the switch and wiring test correctly, diagnose the transfer-case control circuit and module using the manufacturer's procedures.
Common fixes
- Reconnect a loose 4WD selector or transfer-case control connector and clean or repair affected terminals.
- Repair an open or shorted section of selector-switch wiring.
- Replace a faulty 4WD selector switch after verifying its circuit.
- Repair a confirmed transfer-case control circuit or module fault.
Can I keep driving?
If 4WD selection is unreliable, avoid terrain or conditions that require four-wheel drive and do not force mode changes. The vehicle may remain in the wrong drive mode or fail to engage 4WD when needed.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.