P2771 GMC - Four Wheel Drive Low Switch Circuit

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
Comments  |  Add Comment

Possible causes

  • Faulty Four Wheel Drive Low Switch
  • Four Wheel Drive Low Switch harness is open or shorted
  • Four Wheel Drive Low Switch circuit poor electrical connection

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P2771 Gmc Description

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. The transfer case control module controls the 4WD low signal on the low signal circuit. When the operator selects 4WD low, the transfer case control module grounds the signal circuit, and the 4WD low signal voltage on the 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 torque converter clutch (TCC) scheduling.

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.

OBDII Code P2771 Gmc - Four Wheel Drive Low Switch Circuit - AutoCodes.com

Need more help?

Get the P2771 Gmc code diagnosed by a professional: Find a repair shop in you area

Related Information

P2771 GMC Comments

Help us improve AutoCodes.com. Leave a comment below or tell us if the information above help you fix the code. What are the symptoms on your vehicle for the P2771 Gmc code? Have you replaced any parts?
Any information is appreciated. Thanks
Top ⇧