Here are some bulletins from GM pertaining to that trouble code. You really should have the problem diagnosed at a reputable transmission shop and the appropriate repair made.
#07-07-30-025: Information on 4T40-E (MN4) and 4T45-E (MN5) Front Wheel Drive Automatic Transmission Valve Body Reconditioning DTC P0741, P0742, P0751, P0752, P0756, P0757, P1811, Harsh Shift, Slip, No Drive/Reverse - (Oct 1, 2007)
The following new service information outlined in this bulletin will aid technicians in providing easy to follow valve body reconditioning instructions and new illustrations to simplify reassembly of the valve body. The service bulletin will also provide additional service information documents that are related to the 4L6x transmission family.
Important: If valve body cleaning is not required, Do Not disassembly bores unless it is necessary to verify movement of valves.
Call Out Number
Spring, 1-2 Shift Valve
Valve, 1-2 Shift
Solenoid with O-Ring, 1-2 Shift
Solenoid with O-Ring, 2-3 Shift
Spring, 2-3 Shift Valve
Valve, 2-3 Shift
Spring, Torque Signal Regulator
Valve, Torque Signal Regulator
Solenoid, Pressure Control with Two O-Rings and Screen
Filter, Actuator Oil
Valve, Actuator Feed Limit
Spring, Actuator Feed Limit
Spring, 3-4 Shift Valve
Valve, 3-4 Shift
Plug, Bore with O-Ring
Valve, Pressure Regulator Boost
Spring, Pressure Regulator Valve
Valve, Pressure Regulator
Spring, 2-3 Accumulator Valve
Valve, 2-3 Accumulator
Spring, TCC Feed Limit
Valve, TCC Feed Limit
Spring, TCC Control Valve
Valve, TCC Control
Solenoid, TCC with Two O-rings
Valve, TCC Regulated Apply
Spring, TCC Regulated Apply Valve
Notice: Be sure all solenoids are installed with the electrical connectors facing the non-machined (cast) side of the valve body; otherwise, the solenoids will bind against the transmission case as the valve body bolts are tightened and damage may occur.
This PI has been revised to update include 2006 Model Years and different models. Please discard PIP3253A.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Vehicle will not move in either direction. Transmission may show over full. Converter may be empty of fluid. The TCC Control Valve #334 may be stuck in bore. If the valve is stuck in the right position, the converter may not circulate fluid causing no movement.
Some teardowns have identified oil pump rings broken in no/low pressure situations. The PSM or Transmission Fluid Pressure Switch (03-07-30-021) and Driven Sprocket Support Sleeve turned (03-07-30-012) have also been the cause of some "No drive, No reverse" concerns.
2004 model year valve bodies have updated #334 valve that is a larger diameter than the previous one.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
#02-07-30-013E: Incorrect Transmission Shifts, Poor Engine Performance, Harsh 1-2 Upshifts, Slips 1st and Reverse, Torque Converter Clutch (TCC) Stuck Off/On, DTCs P0757, P0741, P0742, P0730, P0756 - (May 20, 2005)
This bulletin is being revised to include additional diagnostic information and clarify model usage. Please discard Corporate Bulletin Number 02-07-30-013D (Section 07 -- Transmission/Transaxle).
Some owners may comment on any one or more of the following conditions:
The most likely cause of the various conditions may be chips or debris:
Important: It has been found that in most cases that the scratches are not severe enough to catch your fingernail.
Important: Clean the valve body with the machined side down so debris may escape.
#02-07-30-021: SES Lamp Illuminated, DTC P0741 - TCC Stuck Off (Reprogram the PCM) - (Apr 22, 2002)
Some customers may comment that the Service Engine Soon lamp is illuminated. The torque converter clutch is no longer operational. The engine speed seems to be higher than normal when driving at highway speeds.
The technicians may find DTC P0741 stored, (TCC stuck off).
Reprogram the PCM with the new service calibration available from Techline in March, 2002 on the TIS 2000 version 22.003 or newer.