Some owners of 2016 GMC Acadia or Terrain vehicles may comment about a condition of no reverse gear, and/or no third gear. The technician may find DTC P0716 and/or P0717 found active or in history.
The condition may be caused by the input shaft speed sensor reluctor ring retainer ring being out of its groove. Replace the retainer ring, input shaft speed sensor reluctor wheel, 3-5 reverse clutch piston, 3-5 reverse and 4-5-6 clutch housing assembly. Inspect and replace other distressed parts as needed. Refer to 3-5 reverse and 4-5-6 clutch housing overhaul in the service manual.