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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 154 (Automatic Transmission - 4L80-E/4L85-E - Service, Diagnosis & Troubleshooting) >> Harsh Shifts

Harsh Shifts

WARNING: This page is about a different car, the 2007 GMC Yukon XL and 2007 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.
Harsh Shifts

Checks Cause
Line Pressure Too high
Pressure Control Solenoid Valve (320)
  • Failed Off
  • Loose connector
PCM Loose connector
Accumulator Piston
  • Leaking
  • Stuck
Accumulator Spring Incorrect
Checkballs Missing
Calibration PROM Incorrect
Check the PCM for current DTCs.