What it means
4WD switch input reads stuck high — short to battery voltage. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The 4WD selector switch sends the driver's chosen mode to the transfer-case control system. This code sets when the switch input is higher than expected, commonly because its signal wire is shorted to battery voltage or a power feed.
Common causes
Most likely first.
- Switch wire shorted to battery voltage
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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 monitor the 4WD selector input on a scan tool while moving through the available switch positions.
- Inspect the selector connector and harness for pin damage, moisture, chafing, or a wire pinched against a power source.
- Gently move the harness while watching the input to check whether it remains high or changes with movement.
- Use the wiring diagram to check the signal circuit for an unintended connection to battery voltage, isolating the circuit as the manufacturer directs.
- If the circuit is sound, test the selector switch and transfer-case control input according to the manufacturer's procedure.
Common fixes
- Repair a signal wire shorted to a power feed or battery supply.
- Clean and secure the selector connector, replacing damaged or corroded terminals.
- Replace a faulty 4WD selector switch after confirming the wiring is intact.
- Repair a confirmed control-circuit fault at the transfer-case module.
Can I keep driving?
Avoid relying on 4WD until the transfer-case mode is confirmed, particularly on slippery or rough surfaces. The control system may misread the requested mode or fail to engage it.
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.