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#08-07-30-001: 4L80E, MT1 and 4L85E, MN8Simplified Valve Body Reconditioning Instructions,DTC P0741, P0742, P0751, P0752, P0756, P0757,P0894, Harsh or Delayed Shifts, Slips, No Drive, NoReverse - (Jan 16, 2008)Subject:4L80E, MT1 and 4L85E, MN8 Simplified Valve BodyReconditioning Instructions, DTC P0741, P0742, P0751,P0752, P0756, P0757, P0894, Harsh or Delayed Shifts,Slips, No Drive, No ReverseModels:1997-2000 Chevrolet Silverado1997-2002 Chevrolet Silverado Chassis Cab1997-2003 Chevrolet Express1997-2006 Chevrolet Suburban1997-2008 Chevrolet Express Panel, Cutaway Vans2001-2006 Chevrolet Silverado 2500 HD, Silverado 3500 HD2002-2006 Chevrolet Avalanche2004-2006 Chevrolet Express 2500 HD, Express 3500 HD2004-2008 Chevrolet W3500/4500 Series Medium Duty Tilt Cab Models1997-2003 GMC Savana1997-2008 GMC Savana Panel, Cutaway Vans2001-2002 GMC Classic Sierra 3500 HD Chassis Cab2001-2006 GMC Sierra 2500 HD, Sierra 3500 HD2001-2007 GMC Yukon XL2002 GMC Sierra Chassis Cab2004-2006 GMC Savana 2500 HD, Savana 3500 HD2004-2008 GMC W3500/4500 Series Medium Duty Tilt Cab Models2006 GMC Yukon Denali XL2007 GMC Savana, Savana HD, Sierra Classic HD2001-2002 Workhorse Chassiswith Hydra-Matic 4L80-E or 4L85-E (RPO'S MT1, MN8)This bulletin is designed to provide easy to follow valve body reconditioning instructions and newillustrations to simplify reassembly of the valve body, and list other service informationdocuments that are related to the 4L80X transmission family.Related Service DocumentPIP3427A - SES light on, DTC P0757, harsh shifts, delayed 2-3 shift, no third gear or slip in thirdor reverse, or a 2-3 shift flare. Debris stuck in the #11 check ball, or a sticking pintle in the 2-3shift solenoid.Inspection Procedure

1. Using the exploded view (Illus. A), inspect each bore for freedom of valve(s) movementand evidence of debris. Pay particular attention to those valves related to the customer’sconcern. IF VALVE BODY CLEANING IS NOT REQUIRED, DO NOT DISASSEMBLE BORESUNLESS IT IS NECESSARY TO VERIFY MOVEMENT OF VALVES.2. Verify movement of the valves in their normal installed position. Valves may becomerestricted during removal or installation. This is normal due to small tolerances betweenthe valves and bores.3. If a valve is restricted and cannot be corrected by cleaning the valve and bore, thenreplace the valve body. Describe the restricted valve on the repair order.Disassembly/Reassembly1. If a valve is restricted by a metal burr from machining that bore, remove the valve andburr, then inspect movement in the valve’s normal position. If no other debris orrestrictions are found, then reassemble the valve body and install in the transmission.2. If the valve body has been contaminated with debris from another transmissioncomponent failure, then disassemble all bores for complete cleaning of all valve bodycomponents. Keeping individual bore parts separated will make reassembly easier. Use thefollowing illustrations for positive identification and location of individual parts.3. Using GM Brake Clean, or equivalent, in a safe and clean environment (clean aluminumpan), clean the valve body and dry it with compressed air. Use appropriate eye protection.4. Clean individual valve body components with GM Brake Clean, or equivalent. Coat eachvalve with clean ATF and reassemble in each bore. Check each valve for free movementduring assembly of each bore.Important: Position the valve body as shown in the following illustrations for positiveidentification and location of individual parts.

Left Side Control Valve Body AssemblyCall Out NumberDescription301Body, Control Valve302Filter, Pressure Control Solenoid Valve Fluid303Pin, Shift Valve, Fluid Filter Bore Plug

304Seat, Low-Reverse Ball Valve305Valve, Low-Reverse Ball307Seal, 3rd Ball Valve Bushing308Valve, 3-4 Shift309Spring, 3-4 Shift Valve310Bolt, Solenoid (1-2 and 2-3 Shift Valve)311Valve Assembly, 2-3 Shift Solenoid312Valve, 2-3 Shift313Valve Assembly, 1-2 Shift Solenoid314Valve, 1-2 Shift315Spring, 1-2 Shift Valve316Plug, Shift Valve Fluid Filter Bore317Filter, Shift Solenoid Valve Fluid318Pin, Low-Reverse Ball Valve Seat334Bushing, Reverse Ball Valve335Bushing, 3rd Ball Valve

Right Side Control Valve Body AssemblyCall Out NumberDescription301Body, Control Valve303Pin, Accumulator Valve Bore Plug, Shift Valve310Bolt, Pressure Control Solenoid Clamp

319Valve, Manual320Valve Assembly, Pressure Control Solenoid321Clamp, Pressure Control Solenoid322Retainer, TCC PWM Solenoid Valve323Valve Assembly, TCC PWM Solenoid324Valve, TCC Regulator Apply325Spring, TCC Regulator Apply Valve327Spring, Actuator Feed Limit Valve328Valve, Actuator Feed Limit329Plug, Accumulator Valve Bore330Spring, Accumulator Valve331Valve, Accumulator333Retainer, Actuator Feed Limit Valve SpringControl Valve Body Spring and Bore Plug Chart (Metric)

Control Valve Body Spring and Bore Chart (Inch)

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions thatmay occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have theequipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletinapplies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from theinformation.

1997-2008 Chevrolet Express Panel, Cutaway Vans 2001-2006 Chevrolet Silverado 2500 HD, Silverado 3500 HD 2002-2006 Chevrolet Avalanche 2004-2006 Chevrolet Express 2500 HD, Express 3500 HD 2004-2008 Chevrolet W3500/4500 Series Medium Duty Tilt Cab Models 1997-2003 GMC Savana 1997-2008 GMC Savana Panel, Cutaway Vans 2001-2002 GMC Classic Sierra 3500 HD Chassis Cab 2001