P279F
Four Wheel Drive (4WD) Range Signal Circuit Low
Transmission / drivetrain
Generic OBD-II
Low
What it means
P279F means the control module sees a lower-than-expected voltage on the four-wheel-drive range signal circuit — the input that reports whether 4WD high or low range is engaged. It usually points to a short to ground, a bad range switch, or a wiring fault. The vehicle still drives normally; you may just lose reliable range selection until it is fixed.
Low
Can I keep driving? Yes — the vehicle drives normally; you may just be unable to select or confirm 4WD high/low range until it is fixed.
Common symptoms
What you'll notice
- Check-engine or 4WD/service-4WD warning light on
- 4WD low (or high) range will not engage or is not confirmed
- 4WD indicator light flashes or stays off when a range is selected
- Transfer case stuck in one range
Common causes
Most likely first
- Short to ground or open in the 4WD range signal circuitLikely
- Faulty 4WD range/mode switch or selectorCommon
- Corroded or damaged connector at the transfer case range sensorCommon
- Faulty transfer case shift actuator or range sensorLess often
- Faulty transfer case control module (less common)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the 4WD range switch and transfer-case connector for damage or corrosion.
- Check the range signal circuit for a short to ground or an open against spec.
- Test the range sensor/switch output as you cycle 4WD high and low.
- Repair wiring or replace the range switch/sensor as indicated.
- Clear the code and confirm 4WD range engagement on a road/off-road test.
FAQ
Quick answers
Is it safe to drive with P279F?+
Yes. Normal on-road driving is unaffected; the fault only concerns the 4WD range signal, so you may lose reliable low/high range selection until it is repaired.
Can I just clear P279F?+
It will return if the switch, sensor, or wiring is still faulty. Fix the circuit or range switch first.
Related codes
Often seen with P279F
Read & clear P279F yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX