GM Service Manual Online
For 1990-2009 cars only

Slips in 1st Gear

Checks

Causes

Forward Clutch Assembly (646-651)

    â€¢ Clutch plates worn
    â€¢ Porosity or damage in forward clutch piston
    â€¢ Forward clutch piston inner and outer seals missing, cut or damaged
    â€¢ Damaged forward clutch housing
    â€¢ Forward clutch housing retainer and ball assembly not sealing or damaged

Forward Clutch Accumulator (353-358)

    â€¢ Piston seal missing, cut or damaged
    â€¢ Piston out of its bore
    â€¢ Porosity in the piston or valve body
    â€¢ Stuck abuse valve

Input Housing and Shaft Assembly (621)

Turbine shaft seals missing, cut or damaged

Valve Body (60)

    â€¢ 1-2 Accumulator valve stuck
    â€¢ Face not flat, damaged lands or interconnected passages
    â€¢ Spacer plate or gaskets incorrect, mispositioned or damaged

Low Roller Clutch (678)

    â€¢ Damage to lugs to inner ramps
    â€¢ Rollers not free moving
    â€¢ Inadequate spring tension
    â€¢ Damage to inner splines
    â€¢ Lube passage plugged

Torque Converter (1)

Stator roller clutch not holding

1-2 Accumulator Assembly (55-57, 104)

    â€¢ Porosity in piston or 1-2 Accumulator cover and pin assembly
    â€¢ Damaged ring grooves on piston
    â€¢ Piston seal missing, cut or damaged
    â€¢ Valve body to spacer plate gasket at 1-2 Accumulator cover, missing or damaged
    â€¢ Leak between piston and pin
    â€¢ Broken 1-2 Accumulator spring

Line Pressure

Refer to Oil Pressure High or Low .

2-4 Servo Assembly (13-28)

4th Servo piston in backward