Replaces the internal harness, A and B shift, EPC and TCC solenoids on 2004-up GM 4L80E and 4L85E units, with a deep-pan filter and pan gasket.
This kit is built around the part most people forget to suspect: the internal wiring harness. On 2004 and later 4L80E and 4L85E transmissions in Chevy and GMC 2500/3500 trucks and Express and Savana vans, a code for one solenoid is often really a cracked wire or a loose pin somewhere between that solenoid and the case connector. Here you get a new 24200161 harness together with both shift solenoids (24230288 and 24230289), the 24248892 EPC solenoid, the 24210864 TCC solenoid, a deep-pan filter and a pan gasket, so every current-carrying part under the pan is new at once.
The harness is the only path between the transmission control module and the valve body. Power and ground for the A and B shift solenoids, the variable current that sets EPC line pressure, and the duty-cycle signal that applies the converter clutch all pass through it. It lies directly over the valve body in hot fluid for the life of the truck, and it is flexed every time the pan comes off. When the insulation hardens and splits, or the terminals at a solenoid or the pass-through connector lose their grip, the module reads an open or a short only some of the time. That is why harness faults look so random: a van that shifts perfectly on a cold morning goes into limp mode after forty minutes on the interstate.
With the codes recorded, back-probe or unplug the case connector and measure each circuit while someone wiggles the harness from the connector toward the transmission control module. A reading that jumps around means the external wiring may be at fault too. Then compare resistance at the case connector with resistance measured directly at each solenoid once the pan is off; if the solenoid is fine on its own and the reading through the harness is not, the harness is the problem. One Transmission Digest case on a 2007 Express 3500 had P0753 and P0758 return even after a new harness and solenoids, so do not skip the outside wiring. Our A and B shift solenoid diagnosis guide has the test steps, and the Express van problems guide covers the van-specific failures.
For GM 4L80E and 4L85E (MT1) units from 2004 on. This kit does not fit 1991-2003 transmissions, because those use a different harness and a different EPC connector. If you are not sure which version is in your truck, look at the plug on the EPC solenoid and the route of the harness in your pan and compare them with the photos, or give us the year and VIN and we will check. You can browse every part we carry for this transmission on the 4L80E shop page.
Drain and remove the deep pan. Pull the filter and make sure its seal leaves the case bore. Unplug the harness at the pass-through and at each solenoid, unclip it from the valve body, then remove the solenoid clips and bolts. Lube every new O-ring with clean ATF before pushing a solenoid into its bore; a dry O-ring can roll and leak line pressure. Lay the new harness on the same path as the old one and secure it with the original clips so it stays clear of the filter. Inspect the pass-through connector's retention tabs while it is out, since a loose connector can be pushed into the pan. Fit the new deep-pan filter and the gasket, torque the pan bolts evenly in a cross pattern, and refill with Dexron VI. Clear codes and road test through all four gears and converter lockup, then recheck the fluid level hot.
If you would rather replace the pan along with the filter, the 4L80E pan kit with filter and gasket fits the job. If clutch slip is part of the complaint, solenoids alone will not fix it; the master rebuild kit with frictions and steels covers the hard parts that wear.
| Fits | |
| Harness | |
| Shift solenoids | |
| EPC solenoid | |
| TCC solenoid | |
| Also includes | |
| Not for |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. It is for 2004 and later units. The 1991-2003 transmissions use a different harness and EPC connector. Choose one of our earlier kits, or send us the VIN and we will match the right one.
It can be. A single cracked wire or loose terminal sets a code for only the solenoid on that circuit. If the solenoid measures correctly on its own but the circuit reads wrong through the case connector, the harness is the problem.
No separate filter is needed. The kit includes a deep-pan filter and a pan gasket, so you can reuse your stock pan if it is straight and clean. Replace the pan only if it is dented or the sealing rail is bent.
Dexron VI. Check the level with the engine running and the fluid at operating temperature, after cycling through all gear positions.
Clear the codes and reset the adaptive values with a scan tool if available. Then drive normally through all four gears and several lockup events so the module adapts to the new EPC solenoid.
