Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer is having trouble talking to the part that controls the 4-wheel drive. It's like when a walkie-talkie isn't working right and you can't hear your friend.
The P279D code is triggered when the vehicle's powertrain control module (PCM) detects an issue with the signal from the 4WD range circuit.
The 4WD range signal circuit is responsible for communicating the current range (high or low) of the 4WD system to the vehicle's PCM. A fault in this circuit can prevent the proper engagement of the 4WD system.
• 4WD system not engaging
• Warning light on the dashboard
• Reduced vehicle performance
• Faulty 4WD range switch
• Damaged wiring or connectors in the 4WD range circuit
• Defective PCM
PCM: Powertrain Control Module
4WD: Four-Wheel Drive
• Inspect the 4WD range switch for damage.
• Check the wiring and connectors for corrosion or damage.
• Use a scan tool to check for additional codes.
• Replace the faulty 4WD range switch.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the PCM if necessary.
• OBD-II scanner
• Multimeter
• Screwdriver set
$150 - $500
Moderate
• Toyota Tacoma
• Ford F-150
• Chevrolet Silverado
• Regularly inspect 4WD system components.
• Avoid harsh off-road conditions that may damage wiring.
• Perform scheduled maintenance checks.
Sensor Issue
• Avoid using 4WD until the issue is resolved.
• Consult a professional mechanic for accurate diagnosis.
Check with your vehicle manufacturer for warranty coverage on drivetrain components.
This code has been more prevalent in vehicles with high off-road usage.
Moderate – It is recommended to address this issue soon to ensure proper 4WD functionality.
Driving with a malfunctioning 4WD system may lead to loss of vehicle control in certain conditions.
• Vehicle must be in 4WD mode.
• Ensure the vehicle is on a stable surface.
The 4WD range switch is typically located on the transfer case of the vehicle.
Q: Can I drive my car with this code?
A: It's possible to drive, but it's recommended to avoid using 4WD until the issue is fixed.
Q: Will this code affect my fuel economy?
A: It might, as the 4WD system could be stuck in a less efficient mode.
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