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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 56 (Automatic Transmission - 6L90 (MYD) - 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 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
Checks Causes
A/Trans Fluid Pan Assembly (29) Verify proper fluid level and condition, inspect transmission assembly for leaks.
Control Valve Upper Body Assembly (304) Inspect for sticking, damaged, or worn R-1/4-5-6 clutch regulator valve (327) and spring (326).
4-5-6 (with Turbine Shaft) Clutch Assembly (56)
  • Inspect for cut, worn, or damaged turbine shaft fluid seal rings (442).
  • Inspect for damaged piston (439), piston dam (437), dam retaining ring (436), and clutch spring (438).
  • Inspect for worn or damaged 4-5-6 clutch plates (432 - 435).
  • Inspect for damaged or leaking clutch housing (441).
  • Inspect for improper selective 4-5-6 clutch backing plate retaining ring (431).
  • Inspect for damaged or distorted turbine shaft.
A/Trans Fluid Pump Seal Assembly (18) Inspect for cut, leaking, or damaged seal.
4 - 5 - 6 Clutch (with Output Carrier Shaft and Dampener) Hub Assembly (58)
  • Inspect the shaft for damage or wear.
  • Inspect the hub assembly (475), dampener (476), and apply plate (477) for wear or damage.
A/Trans Cooling/Lubrication System Inspect transmission oil cooler (radiator) and cooler lines/seals for restrictions, damage, kinks or leaks.
Control Solenoid (w/Body and TCM) Valve Assembly (314) Pressure control solenoid 3 commanded/failed HIGH (off) or leaking - Perform solenoid valve assembly function test. Refer to Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test .
Torque Converter (with Fluid Pump) Housing Assembly (2)
  • Inspect for damaged or scored pump housing (203), cover (219), rotor (217), slide (212), and vanes (216).
  • Inspect for damaged or porous pump cover assembly (219). Inspect pump surfaces for flatness.
  • Inspect for excessive fluid pump rotor (217) clearance or damage. Ensure proper selective rotor is being utilized.
Output Shaft Assembly (70) Inspect for damaged or stripped splines on the output shaft.
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