P2771Four Wheel Drive (4WD) Low Switch Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2771 concerns the input that reports whether the transfer case sits in its low range. GM uses it on 2016 Silverado/Sierra with the MW7 gearbox as a plausibility test in the TCM: if the switch says high range while gear ratio math says low, or the reverse, for at least 0.5 s with fluid between 20 and 130 °C, the Type B code sets. The 2014 LML diesel ECM runs a similar comparison from turbine speed, output speed and ratio. GM's PIP4966B links P2771 on 2007–2011 trucks with Magna transfer cases to a speed-sensor tone wheel shifting on its shaft, or output shaft play, that corrupts the speed signal. Toyota's T-SB-0093-25 shows P2771 with subtype 11 (short to ground) on 2024–2025 Tacoma, fixed with a new shift actuator and breather hose. P2772–P2774 split the fault types.
- What you may notice
- Check engine light, often together with a flashing 4WD indicator
- Erratic speedometer or ABS warning when a speed signal is affected
- Low range not engaging, or transfer case disengaging under load
- Likely causes
- PossibleLoose tone wheel or moving output shaft in the transfer case (GM PIP4966B)
- PossibleTransfer case shift actuator damaged, e.g. by water through the breather (Toyota Tacoma)
- PossibleLow-range switch or position encoder defective
- RareDamaged wiring or corroded connector between switch and control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.