2003 Sierra Trans problems

[mpbspb]

My auto transmission is not shifting from 2 to 3rd. The fluid looks a little dark. The truck has only 50000 miles on it. Any suggestions

[bobcat5544]

Can you give any more info on your trans problem like if it slips, revs high, any other gears not working, it wont shift even if the rpms are up to 5500, is it slow off the line, does the speedo work. any extra info will help

[mpbspb]

It shifts fine from 1st to 2nd. It starts fine from a dead stop and accelerates fine. I had it up to above 5500 rpms but it still wont shift into 3rd. The speedo works fine. There is no slipping that i can tell. I had a local trans shop to look at it and they said the oil looked burnt and i needed to rebuild or replace. The truck has been well cared for and it just seems premature to have to replace a trans at 55000 miles.

[bobcat5544]

Here are the posiblities

The lines in bold are the most likely parts that can cause your problem

 

Valve Body Assembly

• 2-3 Shift valve train stuck

• Gaskets or spacer plate incorrect, mispositioned or damaged

• 2-3 Accumulator valve stuck

• Chips in servo feed oil, orifice #7 in spacer plate

 

Input Housing Assembly

• 3-4 clutch or forward clutch plates worn

• Excessive clutch plate travel

• Cut or damaged 3-4 clutch or forward clutch piston seals

• Porosity in input clutch housing or piston

• 3-4 clutch piston checkball stuck, damaged or not sealing

• Restricted apply passages

• Forward clutch piston retainer and ball assembly not seating

• Sealing balls loose or missing

• Input housing (621) cracked or broken

 

Case

• 3rd accumulator retainer and ball assembly not seating

 

2-4 Servo Assembly

• 2nd apply piston seals missing, cut or damaged

 

Oil Pump

• Stator shaft bushings scored or off location

 

Orificed Cup Plug

• Missing or blown out

[mpbspb]

Wow That just went way over my head. Sounds like it will have to be broken down to repair. I was hoping for a easy fix to the problem.

[bobcat5544]

Wow That just went way over my head. Sounds like it will have to be broken down to repair. I was hoping for a easy fix to the problem.

 

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If I had to bet on it I would say it is 2-3 shift valve, but im not there to test it

 

From what you stated I highly doubt you need a trans overhaul.

[mpbspb]

Where is the shift valve located? Same as shift solenoid? Im not a mechanic but attempt to do alot of repairs myself. Would a diagnostic test pick that up?

[stev0]

I have a 2003 sierra z 71 I believe the transmission is the 4l60E. It starts in third and will not shift at all! Any suggestions. 156k miles. Oil is a little dark but no odor. I tried to get codes but will not give me any even though the engine light is on. Any suggestions would be greatly appreciated. Thanks in advance.

Steve