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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 16 (Automatic Transmission - 4L60-E/4L65-E/4L70-E - Service, Diagnosis & Troubleshooting) >> Slipping or Harsh 1-2 Shift

Slipping or Harsh 1-2 Shift

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Slipping or Rough 1-2 Shift

Checks Causes
Valve Body Assembly (60)
  • Mislocated valve body to spacer plate check ball or check balls.
  • 1-2 Shift valve train stuck due to sediment
  • Gaskets or spacer plate incorrect, mispositioned or damaged
  • 1-2 Accumulator valve stuck or damaged
  • Face not flat
  • 4-3 sequence valve stuck or damaged
  • #1 or #8 check ball missing or mis-located
  • 1-2 accumulator valve bushing rotated 180°
2-4 Servo Assembly (13-28)
  • Apply pin too long or too short
  • 2nd servo apply piston seal missing, cut or damaged
  • Restricted or missing oil passages
  • Servo bore in case damaged
2nd Accumulator (55-57, 104)
  • Porosity in 1-2 accumulator cover or piston
  • Piston seal or groove damaged
  • Nicks or burrs in 1-2 accumulator housing
  • Missing or restricted oil passage
  • 1-2 accumulator piston spring not seated
  • Rough finish in 1-2 accumulator bore in case
  • A cracked 1-2 accumulator piston - allowing fluid to leak by
2-4 Band (602) Worn or mispositioned
Oil Pump Assembly (4) or Case (103) Faces not flat