P279B 2016 GMC Sierra Code - Four Wheel Drive Low 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
- P279B 2016 GMC Sierra indicates Four Wheel Drive Low 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 P279B 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 P279B 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 P279B 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 P279B 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 P279B 2016 GMC Sierra Code
1. What does the OBDII code P279B mean on a 2016 GMC Sierra?
The P279B code indicates a performance issue with the Four-Wheel Drive (4WD) Low Range system, meaning the vehicle's computer has detected that the 4WD Low Range is not engaging or operating as expected.
2. What are the common symptoms of a P279B code on a 2016 GMC Sierra?
Symptoms may include the 4WD Low not engaging, a 4WD warning light on the dashboard, reduced off-road capability, or difficulty in transitioning between 4WD modes.
3. What causes the P279B code to appear on a 2016 GMC Sierra?
Common causes include a malfunctioning transfer case motor, faulty 4WD control module, wiring or electrical issues, or mechanical problems within the transfer case.
4. Can I still drive my 2016 GMC Sierra with a P279B code?
Yes, but the 4WD Low function may not work, which could limit performance in off-road or low-traction conditions. It's advisable to address the issue promptly to avoid further damage.
5. How do I diagnose the P279B code on a 2016 GMC Sierra?
Diagnosis involves checking for stored codes, inspecting the transfer case motor and wiring, testing the 4WD control module, and verifying the mechanical integrity of the transfer case.
6. How can I fix the P279B code on my 2016 GMC Sierra?
Repairs may include replacing the transfer case motor, repairing damaged wiring, reprogramming or replacing the 4WD control module, or servicing the transfer case.
7. What tools are needed to troubleshoot a P279B code on a GMC Sierra?
You'll need an OBDII scanner, a multimeter for electrical testing, and possibly specialty tools for accessing and removing the transfer case motor.
8. How much does it cost to repair a P279B code on a 2016 GMC Sierra?
Repair costs vary, but replacing a transfer case motor typically ranges from $500 to $1,200, depending on labor rates and parts pricing.
9. Can low transfer case fluid cause the P279B code on a GMC Sierra?
Yes, insufficient or contaminated transfer case fluid can cause mechanical issues that trigger the P279B code. Checking and replacing the fluid may help resolve the issue.
10. Does the P279B code require a software update on a 2016 GMC Sierra?
In some cases, a software update for the 4WD control module may resolve the issue. Check with your dealership or repair technician for the latest updates.
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