4L80E Transmission Solenoid Kit EPC Shift TCC 4-Piece

Four-piece electrical solenoid set for the GM 4L80E and 4L85E, covering the two shift solenoids (A and B), the TCC lockup solenoid, and the EPC (electronic pressure control) solenoid. It replaces OE numbers 24230288 and 24230289 (shift), 24210864 (TCC) and 24243101 (EPC) on 1991-2003 units with the MT-1 RPO code. All four are new, not rebuilt.

The 4L80E lives behind the 7.4L, 6.5L diesel, 5.7L and 8.1L in 3/4- and 1-ton trucks, vans and motorhomes, so these solenoids see heat and mileage. Shift solenoid failure shows up as no 1-2 or no 2-3, stuck in second, or codes P0751/P0756. A dead TCC solenoid gives you no lockup, higher converter temps and a P0740. A worn EPC is the one that ruins clutches: line pressure drops, shifts go soft and mushy or slam depending on which way it drifts, and it often sets P1810 or P0748.

Because all four sit on the valve body, the pan and filter come off for any one of them, so replacing the whole set on a unit with 150k on it costs no extra labor. Drop the pan, pull the filter, unplug the internal harness at each solenoid, unbolt the retainer clips, and swap them one at a time so nothing gets crossed. Check the O-rings seat clean in their bores, and torque the pan bolts evenly on a fresh gasket. Refill with DEXRON, then clear codes and relearn on a road test.

Note the year split: this set is for 1991-2003 4L80E and 4L85E. The 2004-and-up units use a different connector and solenoid family, so verify the RPO tag before ordering.