What are the common causes of P279D?

A 4WD range switch sending no signal to the module. An open or shorted wire in the 4WD range signal circuit. Corrosion in the 4WD range switch connector. A failing 4WD range sensor or switch. Low battery voltage upsetting the four wheel drive module.

Check battery voltage and charge it if low. Inspect the 4WD range switch and its connector. Test the 4WD range signal wire for opens and shorts. Shift through the 4WD ranges and watch the range signal live data. Replace the 4WD range switch if the signal is missing. Clear the code and retest.

P279D

Four Wheel Drive (4WD) Range Signal Circuit

System: Transmission (P code)
Lamp: Check Engine Light
Category: Powertrain - Transmission

What it means

P279D means Four Wheel Drive (4WD) Range Signal Circuit.

Check these first

A 4WD range switch sending no signal to the module
An open or shorted wire in the 4WD range signal circuit
Corrosion in the 4WD range switch connector
A failing 4WD range sensor or switch
Low battery voltage upsetting the four wheel drive module

What to do next

Check battery voltage and charge it if low
Inspect the 4WD range switch and its connector
Test the 4WD range signal wire for opens and shorts
Shift through the 4WD ranges and watch the range signal live data
Replace the 4WD range switch if the signal is missing
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.