This 4L80E-HD2 Reprogramming Kit fits 1991 to 2013 General Motors vehicles equipped with the 4L80E and 4L85E automatic transmission.  Common complaints on this transmission are, no upshifts, soft 2-3 shift, burnt direct frictions, broken hard parts as well as gear ratio and solenoid performance codes.

The boost valve assembly is notorious for wear causing both low pressure as well as runaway boost pressure. With the low boost pressure problem, the resulting complaints are a soft 2-3 shift, direct clutch failure as well as the gear ratio and solenoid performance codes. On the other hand, the runaway boost pressure problem can result in a costly broken case, direct drum and piston failure.

Features and benefits:

This TransGo Reprogramming Kit includes valve body, pump and internal components that are calibrated to work in concert with an elevated line pressure curve that will greatly improve the overall durability and shift feel of the transmission. Also, the laminated triple separator plate provides dual feed for the 3^rd gear clutch without having to dismantle the transmission. Dual feeding the 3^rd gear clutch triples the torque capacity of the 3^rd gear clutch which is the Achilles heel of this transmission. In addition, the included highly improved wide land design boost valve and bushing resists wear so that pressure regulation functions consistently for the long haul. Lastly, the EPC boost pressure relief valve system provided helps protect against accidental runaway boost pressure to stop the case and direct drum failure.

Corrects/Prevents/Reduces:

• High pressure parts breakage
• Soft 2-3 shift
• Burnt direct clutch
• Slow 3-2 downshift
• No upshifts
• Harsh 1-2 shift
• Low pressure due to solenoid filter breakup
• Codes 39, 68, 85, 86, 87, P0731, P0732, P0733, P0734, P0751, P0756, P0894 and P1870

Includes:

• Heavy duty intermediate case snap ring
• (2) Accumulator valve springs, end plug and O-ring
• Actuator filter tapered plug, O-ring, spring and end plug
• Relief valve system plate, valve, spring, e-clip and nuts
• Laminated triple separator plate
• Valve body and accumulator body gaskets
• (2) Drill bits
• 3^rd accumulator spring
• USA-made hardened boost valve and bushing
• Pressure regulator valve spacer, washer, springs and snap ring
• New stronger 4^th feed bolt and washer
• 1-2 accumulator spring
• (16) Direct clutch return springs