4L80E Transmission Solenoid Kit with Harness and Sensors

This is a complete nine-piece solenoid service set for the GM 4L80E and 4L85E with RPO codes MT1 and MN8, 1997 through 2003. It covers every electrical piece that bolts to or plugs into the valve body: the TCC/PWM lockup solenoid 24210864, the EPC line pressure solenoid 24220158, the 1-2 / 3-4 A shift solenoid 24230288, the 2-3 B shift solenoid 24230289, the internal wiring harness 24222798, the fluid filter with pan seal 24210956, the pan gasket 8677743, and the input and output speed sensors 24203876.

The reason to buy the set instead of a single solenoid is that these parts age together. Once one shift solenoid has enough hours on it to stick, the other one and the harness pass-through connector are usually the same age and the same heat cycles behind. A worn EPC solenoid drops line pressure, which lets the clutches slip and cook the fluid; a lazy TCC/PWM solenoid shows up as converter shudder at light throttle around 45 to 55 mph, or as RPM that will not settle on the highway. Speed sensor dropouts throw P0720 and P0722 and put the transmission in limp with no shift at all.

On the bench or on a lift, it is a pan-off job. Drain the pan, pull it and the filter, and unplug the internal harness from each solenoid and from the case connector. The A and B shift solenoids come off the valve body with a single retaining bolt and bracket each; the TCC/PWM and EPC solenoids pull from their bores with a light twist. Replace all four, lay in the new harness, clip the speed sensors in, install the new filter and seat its seal square in the pump bore, and set the pan on the new gasket. Torque the pan bolts evenly and refill with Dexron VI.

Do the pressure and shift checks after the fill. If the truck was throwing P0748, P0753, P0758 or P1860 before the job, clear the codes and drive it through all four gears plus a lockup cycle before you call it done. This kit is new, not remanufactured, and the speed sensors are what separate it from the four-piece solenoid-only sets.