CVO 10/13/2010Google it and found the answer.
GM has issued a TSB # 01-07-30-036C to cover all 2001-05 passenger cars and light duty trucks equipped with the 4L60-E or 4L65-E transmission. If the vehicle shows trouble code P0756, it’s a sign of a mechanical failure, not a problem an electrical connector. GM says that a small orifice on the top of the spacer plate can get clogged with debris and cause this trouble code. The repair involves removing the valve body spacer plate and inspecting orifice #29. The code can also be caused by a cracked, broken, or leaking 2-3 shift solenoid. A stuck or hung-up 2-3 shift valve could also bring up this code. If the vehicle is still in warranty, it will be covered. Otherwise, you will have to discuss the cost of repair with your dealer to see if GM is willing to pay for it as a goodwill gesture.
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