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Home >> Chevrolet >> 2017 >> Spark LT, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 79 (Automatic Transmission - 6T45 (MH7) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> No Fourth, Fifth, and Sixth Gear

No Fourth, Fifth, and Sixth Gear

WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.
Checks Causes
4 - 5 - 6 Clutch Assembly
  • Inspect for damaged, stripped or sheared splines on 4 - 5 - 6 Clutch Plates (526 - 528), Backing Plate (529)
  • Inspect for broken or fatiqued 4 - 5 - 6 Clutch Waved Plate (525)
  • Inspect for damaged or broken 4 - 5 - 6 Clutch Piston (520) and Piston Seals (518, 519, 521)
  • Inspect for broken or fatigued 4 - 5 - 6 Piston Return Spring (522)
  • Inspect for broken or disengaged 4 - 5 - 6 Backing Plate Retainer (532)
  • Inspect for damaged or broken 4 - 5 - 6 Clutch Dam Piston (523) and piston seals damaged, worn or delaminating
  • Inspect for broken or disengaged 4 - 5 - 6 Clutch Dam Retainer (524)
  • Inspect for stripped or sheared splines on the Reaction Carrier Hub (531)
  • Inspect for stripped or sheared splines on 3 - 5 Rev/4 - 5 - 6 Housing to Turbine Shaft (516)
  • Inspect for loose, worn or damaged 3 - 5 Rev/4 - 5 - 6 Housing Bushing
  • Inspect for broken, porous or improper surface finish or plugged oil passages of the 3 - 5 Rev/4 - 5 - 6 Housing (516)
Transmission Case Assembly Inspect the input shaft support (56) for missing or damaged fluid ring seals (58).
Control Valve Body Assembly Inspect the reverse and 4-5-6 regulator valve (411) and ball check valve (404) for debris and stickyness.
Control Solenoid (w/Body and TCM) Valve Assembly Check the pressure control solenoid 3 (R1/456) for proper operation. Refer to Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test .