4L80E Master Solenoid Kit with Harness and Filter, 2004-Up

A complete electrical overhaul for the 2004-and-later GM 4L80E and 4L85E (RPO MT1 and MN8). Everything in the kit is new: the TCC/PWM solenoid (24210864), EPC force motor (24248892), 1-2/3-4 A shift solenoid (24230288), 2-3 B shift solenoid (24230289), internal wiring harness (24200161), input/output speed sensor (24203876), plus the filter with seal (24210956) and pan gasket (8677743).

What it fixes: a failing TCC/PWM solenoid gives highway shudder and RPM hunting at lockup, a worn EPC lowers line pressure and lets clutches slip and burn, and a sticking shift solenoid gives missed or wrong-gear shifts. A cracked internal harness gives intermittent codes that come and go with temperature. Doing the solenoids, harness and sensor together clears out the usual electrical failure points in one pan drop.

On the bench: drop the pan, pull the filter and seal, unplug and remove the internal harness, then unbolt the EPC, TCC/PWM and the two shift solenoids from the valve body. Install the new parts with fresh O-rings, route the new harness exactly like the original, fit the new filter and seal into the case bore, and install the pan with the new gasket. Refill with Dexron VI and check level hot.

Built for the 2004-up case design; earlier 1991-2003 4L80E units use a different harness and solenoid layout.