P279C 2015 GMC Sierra Code - Four Wheel Drive Neutral Range Performance
Quick Answer
The Engine Control Module (ECM) uses the following two ways to determine if the transfer case is in 4WD Low, 4WD High, or Neutral. Common causes include Reprogram Engine Control Module (ECM), Faulty Engine Control Module, Engine Control Module harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P279C 2015 GMC Sierra indicates Four Wheel Drive Neutral Range Performance.
- Common causes
- Common causes include Reprogram Engine Control Module (ECM), Faulty Engine Control Module, Engine Control Module harness is open or shorted.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P279C 2015 GMC Sierra Description
1. The first way is to compare the transmission output speed sensor to the transfer case output speed sensor in order to calculate the transfer case range.
2. The second way is to use a LAN message sent by the transfer case shift control module to the ECM.
The ECM uses this message to determine motor torque required and transmission shifting.
The internal fault detection is handled inside the control module. No external circuit diagnosis is involved.
If the first way and second way of determining transfer case range do not match while in 4WD Low, 4WD High or Neutral, then the Diagnostic Trouble Code (DTC) is set.
What are the Possible Causes of the DTC P279C 2015 GMC Sierra?
- Reprogram Engine Control Module (ECM)
- Faulty Engine Control Module
- Engine Control Module harness is open or shorted
- Engine Control Module circuit poor electrical connection
- Transmission internal mechanical problems
How to Fix the DTC P279C 2015 GMC Sierra?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P279C 2015 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P279C 2015 GMC Sierra Code
What does the OBDII code P279C mean on a 2015 GMC Sierra?
Code P279C indicates an issue with the Four-Wheel Drive Neutral Range Performance, meaning the transfer case is not properly engaging or functioning as expected in neutral mode.
What are common symptoms of code P279C in a 2015 GMC Sierra?
Symptoms may include the four-wheel-drive system not engaging properly, a warning light on the dashboard, inability to shift into neutral range, or unusual noises from the transfer case.
What causes the P279C code to appear on a 2015 GMC Sierra?
Common causes include a faulty transfer case control module, damaged wiring or connectors, a malfunctioning shift motor, or mechanical issues within the transfer case.
Can a weak battery or low voltage trigger the P279C code?
Yes, low voltage or a weak battery can affect the transfer case control module's operation, potentially triggering the P279C code.
How can I diagnose the P279C code on my 2015 GMC Sierra?
Start by scanning the vehicle with an OBDII tool, inspecting the transfer case wiring and connectors for damage, and testing the transfer case shift motor and control module for proper functionality.
Is it safe to drive with a P279C code on a 2015 GMC Sierra?
Driving with this code may not be safe if the four-wheel-drive system is malfunctioning, as it could cause drivetrain issues or leave the vehicle stuck in an undesired mode.
How can I fix the P279C code on my 2015 GMC Sierra?
Repairs may include replacing a faulty transfer case control module, repairing damaged wiring, replacing the shift motor, or addressing internal transfer case issues.
What tools are needed to troubleshoot the P279C code?
You’ll need an OBDII scanner, a multimeter for testing electrical connections, and possibly specialty tools for accessing and repairing the transfer case components.
Can software updates fix the P279C code on a 2015 GMC Sierra?
In some cases, reprogramming or updating the transfer case control module software may resolve the issue if it’s caused by a software-related glitch.
How much does it cost to repair the P279C code on a 2015 GMC Sierra?
Repair costs can vary, ranging from $100 to $1,500, depending on whether the issue involves simple electrical repairs, component replacements, or major transfer case repairs.
Discuss the causes and fixes for P279C 2015 GMC Sierra OBDII Code
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