P2771 2017 GMC Sierra Code - Four Wheel Drive Low Switch Circuit
Quick Answer
For vehicles equipped with an active transfer case, the four-wheel drive (4WD) low circuit consists of the Powertrain Control Module (PCM), a transfer case control module, and the circuit wiring. Common causes include Faulty Transfer Case Shift Control Switch, Transfer Case Shift Control Switch harness is open or shorted, Transfer Case Shift Control Switch circuit poor electrical connection. 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
- P2771 2017 GMC Sierra indicates Four Wheel Drive Low Switch Circuit.
- Common causes
- Common causes include Faulty Transfer Case Shift Control Switch, Transfer Case Shift Control Switch harness is open or shorted, Transfer Case Shift Control Switch circuit poor electrical connection.
- 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 P2771 2017 GMC Sierra Description
For vehicles not equipped with an active transfer case, the 4WD low circuit consists of the PCM, a transfer case switch, and the circuit wiring. The transfer case switch controls the 4WD low signal on the signal circuit. When the operator selects 4WD low, the transfer case switch closes, and the 4WD low signal voltage on the signal circuit changes from ignition voltage to zero volts. The PCM then compensates for transfer case gear reduction in the transmission output shaft speed (OSS) sensor signal. The PCM uses the transmission OSS sensor signal to adjust shift points, line pressure, and TCC scheduling.
What are the Possible Causes of the DTC P2771 2017 GMC Sierra?
- Faulty Transfer Case Shift Control Switch
- Transfer Case Shift Control Switch harness is open or shorted
- Transfer Case Shift Control Switch circuit poor electrical connection
How to Fix the DTC P2771 2017 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 P2771 2017 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 P2771 2017 GMC Sierra Code
1. What does the OBDII code P2771 mean on a 2017 GMC Sierra?
Code P2771 indicates an issue with the Four-Wheel Drive (4WD) Low Switch Circuit, which monitors the functionality of the transfer case's low gear mode.
2. What are the common symptoms of code P2771 in a 2017 GMC Sierra?
Symptoms may include the 4WD Low mode not engaging, the 4WD warning light illuminating, and reduced off-road performance.
3. What causes the P2771 code in a 2017 GMC Sierra?
Common causes include a faulty 4WD low switch, damaged wiring or connectors, a malfunctioning transfer case control module, or a mechanical failure in the transfer case.
4. Can you drive with the P2771 code active in a 2017 GMC Sierra?
Yes, you can typically drive the vehicle, but 4WD Low mode may not function, potentially reducing off-road capability or performance in low-traction situations.
5. How is the P2771 code diagnosed?
A technician will inspect the 4WD low switch, wiring, and connectors, check for other related codes, and test the transfer case control module for proper operation.
6. How do you fix the P2771 code on a 2017 GMC Sierra?
Repairs may involve replacing the 4WD low switch, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the transfer case control module.
7. Is the P2771 code related to the transfer case motor?
While not directly related, a faulty transfer case motor could contribute to issues with 4WD Low engagement and should be tested during diagnosis.
8. Does the P2771 code affect all 4WD modes in a 2017 GMC Sierra?
No, it typically only affects the 4WD Low mode. Other 4WD modes like 4WD High should still function unless additional issues are present.
9. How much does it cost to fix the P2771 code on a 2017 GMC Sierra?
Repair costs vary but may range from $100 to $500 depending on whether the issue is with the switch, wiring, or control module.
10. Can clearing the P2771 code temporarily fix the issue?
Clearing the code may turn off the warning light temporarily, but the underlying issue must be addressed to prevent it from returning.
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