trans clunk

[nightowl]

I have a 2003 silverado z71.

The first dealer I took it to for the 2nd/ 3rd upshift/downshift clunk gave me the tech bulliton and that was it. I had called gm customer service and asked about the clunk, I hadn't done any research on it yet and didn't know about this site. They said take it to another dealer. So I finally did that today and they did a shift upgrade in the computer. It seems better, I'll see how it does this weekend.

[Tolliverme]

Please tell more about the tech bulliten that they gave you and about the shift upgrade. I had an O! with 2 to 3 shift problems and my 03 acts funny at times.

[budhayes3]

Here's a couple that I got from AllData:

 

A/T - 4L60-E/4L65-E, 2-3/3-2 Shift Clunk Explanation

 

Bulletin No.: 01-07-30-042B

 

Date: January 16, 2004

 

INFORMATION

 

Subject:

Information on 2-3 Upshift or 3-2 Downshift Clunk Noise

 

Models:

2004 and Prior Light Duty Trucks

2003-2004 HUMMER H2

with 4L60E or 4L65E Automatic Transmission (RPOs M30, M32)

 

Supercede:

 

This bulletin is being revised to add the 2004 model year. Please discard Corporate Bulletin Number 01-07-30-042A (Section 07 Transmission/Transaxle).

 

Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift.

 

During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in the transfer case.

 

This is a normal condition. No repairs should be attempted.

 

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A/T - Harsh 1-2 and 3-2 Shifts

 

File In Section: 07 - Transmission/Transaxle

 

Bulletin No.: 99-07-30-009

 

Date: June, 1999

 

TECHNICAL

 

Subject:

Harsh 1-2 and 3-2 Shifts (Reprogram PCM)

 

Models:

1999 Chevrolet and GMC C/K Models (Silverado and Sierra) with 4.8 L or 5.3 L Engine (VINs V, T - RPOs LR4, LM7) and Hydra-Matic 4L60-E Transmission (RPO M30)

 

Condition

Some customers may comment about a harsh 1-2 upshift during acceleration at light to moderate throttle opening. It is characterized by a "Bump" at the end of the shift. A similar condition may exist during a "Power-on" 3-2 downshift.

 

Cause

Condition may be caused by insufficient line pressure to complete the shift caused by component variation.

 

Correction

Reprogram the Powertrain Control Module (PCM) with the calibrations listed in this bulletin.

 

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Hope this helps.