2000 GMC C2500



February, 25, 2010 AT 6:01 PM

Transmission problem
2000 GMC C2500 V8 Four Wheel Drive Automatic 78000 miles

when reverse gear is selected, the truck will not engage. Sounds like it is still in neurtral. Worked fine one day and not the next.

1 Answer



February, 25, 2010 AT 10:48 PM

The problem is internal to the trans, and there are several possibilities. Does it have all forward gears? Here is the list of probables for No reverse, first chart is for 4L80E trans, and second for 4L60E.

No Reverse

Case (7)
The rear band anchor pin is broken or the pin is not positioned.

Center Support (640)
Leaking at the case, or the support is broken.

Center Support Seal (639)

Center Support Bolt (25)
" The bolt is loose or broken.

" The feed hole is blocked.

Rear Band (657)
Broken, worn, or not anchored

Rear Band Apply Pin (73)
The pin is too short or the pin is binding in the case.

Piston (65)
Binding in the case

Seal (66)
Leaking, damaged, or worn

Gasket (63)
Damaged or displaced

Cover (62)

Bolts (61)
Broken, loose, or missing


Fluid Pressure
Too low

Direct Clutch Components

Reaction Plates (618)
The splines are worn.

Friction Plates (611)
The splines or the friction are worn.

Spring Assembly (607)

Housing (623)

Piston (619)

Seal (620, 621, 622)

Ball Check

No Reverse or Slips in Reverse
No Reverse or Slips in Reverse Checks

Input Housing Assembly
" 3-4 Apply ring stuck in applied position

" Forward clutch not releasing

" Turbine shaft seals missing, cut or damaged

Manual Valve Link

Valve Body Assembly
" 2-3 Shift valve stuck

" Manual linkage not adjusted

" Spacer plate and gaskets incorrect, mispositioned or damaged

" Lo overrun valve stuck

" Orificed cup plug restricted, missing or damaged

Reverse Input Clutch Assembly
" Clutch plate worn

" Reverse input housing and drum assembly cracked at weld

" Clutch plate retaining ring out of groove

" Return spring assembly retaining ring out of groove

" Seals cut or damaged

" Restricted apply passage

" Porosity in piston

" Belleville plate installed incorrectly

" Excessive clutch plate travel

" Oversized housing

Lo and Reverse Clutch
" Clutch plates worn

" Porosity in piston

" Seals damaged

" Return spring assembly retaining ring mispositioned

" Restricted apply passage

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