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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 597 (AUTOMATIC TRANSAXLE, 4T65-E DIAGNOSTICS (TROUBLESHOOTING))TROUBLESHOOTINGFIRST GEAR ONLY
1999 GMC Forward Control 5.7 R, Automatic

First Gear Only

1999 GMC Forward Control 5.7 R, AutomaticSECTION First Gear Only
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
First Gear Only

Checks Cause
DEFINITION: The transmission only provides first gear in Drive range. The vehicle accelerates from a stop in first gear and does not upshift. First gear ratio is 2.921:1.
Control Valve Body Assembly
  • The 1-2 shift valve (318) is stuck or binding.
  • Debris is found in the control valve body (301) or the control valve body spacer plate and gasket assembly (396)
  • The spacer plate and gaskets (369-371) are misassembled.
Second Clutch Assembly
  • A missing or not seated second clutch backing plate retaining ring (627)
  • A missing or misassembled second clutch backing plate (626)
  • Worn, damaged, or misassembled clutch plates (623-625)
  • A missing or not seated second clutch spring retaining ring (622)
  • A damaged spring assembly (621) or piston (620)
  • A missing or damaged second clutch housing ball check valve assembly (618)
  • A damaged second clutch housing assembly (617)
Reverse Reaction Drum Damaged splines of the reverse reaction drum (669)
RENDER: 1.0x

NO RELATED

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.