P279A 2014 GMC Sierra Code - Four Wheel Drive High 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
- P279A 2014 GMC Sierra indicates Four Wheel Drive High 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 P279A 2014 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 P279A 2014 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 P279A 2014 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 P279A 2014 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 P279A 2014 GMC Sierra Code
1. What does the OBDII code P279A mean for a 2014 GMC Sierra?
P279A indicates a "Four-Wheel Drive High Range Performance" issue, meaning the vehicle's control module has detected a problem with the 4WD system while in high range.
2. What are the common symptoms of a P279A code on a 2014 GMC Sierra?
Symptoms may include the 4WD system not engaging or disengaging properly, difficulty shifting into high range, a 4WD warning light on the dashboard, or reduced off-road performance.
3. What causes the P279A code to appear on a 2014 GMC Sierra?
Possible causes include a faulty transfer case motor, damaged wiring or connectors, low or contaminated transfer case fluid, or a malfunctioning transfer case control module.
4. How can I diagnose a P279A code on my 2014 GMC Sierra?
Start by scanning the vehicle with an OBDII tool to confirm the code. Inspect the transfer case motor, wiring, and fluid condition. Check for physical damage to components or electrical connectors.
5. Can low transfer case fluid cause a P279A code on a 2014 GMC Sierra?
Yes, low or contaminated transfer case fluid can cause the transfer case to perform poorly, triggering a P279A code.
6. How do I fix the P279A code on a 2014 GMC Sierra?
Repairs may include replacing the transfer case motor, repairing damaged wiring, flushing and refilling the transfer case fluid, or replacing the transfer case control module if defective.
7. Is it safe to drive with a P279A code on a 2014 GMC Sierra?
It may be safe to drive in 2WD mode, but 4WD functionality could be compromised. Avoid off-road driving until the issue is resolved.
8. How much does it cost to repair a P279A code on a 2014 GMC Sierra?
Repair costs vary depending on the cause. Transfer case motor replacement can range from $300 to $700, while fluid changes or wiring repairs may cost less.
9. Can a P279A code be caused by a software issue in the 2014 GMC Sierra?
Yes, a software glitch in the transfer case control module could potentially cause the code. Updating the module's software may resolve the issue.
10. Will clearing the P279A code fix the problem on a 2014 GMC Sierra?
Clearing the code without addressing the root cause will likely result in the code returning. Proper diagnosis and repair are necessary for a permanent fix.
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