P279A 2016 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 2016 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 2016 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 2016 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 2016 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 2016 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 2016 GMC Sierra Code
1. What does the OBDII code P279A mean on a 2016 GMC Sierra?
The P279A code indicates a "Four Wheel Drive High Range Performance" issue, meaning the vehicle’s 4WD system is not performing as expected in high range mode.
2. What are common symptoms of P279A on a 2016 GMC Sierra?
Symptoms may include the 4WD system not engaging or disengaging properly, warning lights on the dashboard, reduced traction, or difficulty switching between 2WD and 4WD modes.
3. What causes the P279A code on a 2016 GMC Sierra?
Common causes include a faulty transfer case motor, damaged wiring or connectors, software issues in the transfer case control module, or mechanical problems in the transfer case.
4. Can I drive my 2016 GMC Sierra with the P279A code?
It may be possible to drive, but performance could be compromised, especially in off-road or low-traction conditions. Prolonged driving without repair could cause further damage.
5. How is the P279A code diagnosed on a 2016 GMC Sierra?
A technician will use a scan tool to confirm the code, inspect the transfer case motor, wiring, and connectors, and possibly test the transfer case control module for faults.
6. What repairs are needed to fix the P279A code on a 2016 GMC Sierra?
Repairs may include replacing the transfer case motor, repairing or replacing damaged wiring, updating the transfer case control module software, or addressing internal transfer case issues.
7. How much does it cost to fix the P279A code on a 2016 GMC Sierra?
Repair costs can vary widely, ranging from $200 for a simple wiring repair to $1,000 or more if the transfer case motor or control module needs replacement.
8. Can a software update fix the P279A code on a 2016 GMC Sierra?
Yes, in some cases, a software update for the transfer case control module can resolve the issue if the problem stems from programming errors.
9. What tools are needed to troubleshoot the P279A code?
Troubleshooting typically requires an OBDII scan tool, a multimeter for checking electrical circuits, and possibly specialized tools for transfer case component inspection.
10. How can I prevent the P279A code from recurring on my 2016 GMC Sierra?
Regular maintenance of the transfer case, ensuring proper fluid levels, inspecting wiring for damage, and addressing 4WD system issues promptly can help prevent recurrence.
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