New 4L80E master kit with TCC, EPC and shift solenoids, internal harness, speed sensor, filter and gasket for 2004-up GM MT1 and 4L85E units.
Late-model 4L80E trucks and vans, the 2004-and-newer Express and Savana 2500/3500 heavy vans especially, tend to wear out their electrical parts as a group: intermittent shift codes that only show up hot, converter shudder on the highway, a harness that cracks where it flexes near the case connector. This master kit covers every one of those failure points for 2004-up MT1 4L80E and MN8 4L85E units, with new solenoids, a new 24200161 internal harness, the 24203876 speed sensor and the filter and pan gasket, so the whole electrical side gets done on a single pan drop.
Inside the pan, the controller runs the transmission through four solenoids. The EPC force motor (24248892 in this kit) takes a varying current from the module and works backwards from intuition: more current means less line pressure, and when the module loses control of it, it drives line pressure to maximum on purpose. The A (24230288) and B (24230289) solenoids are simple on/off valves whose on/off combinations select the four forward gears. The TCC/PWM solenoid (24210864) pulses the converter clutch on smoothly instead of slamming it. The internal harness carries all of them to the case pass-through connector, and the speed sensor tells the controller what the gearset is really doing so it can check each shift.
Read the codes and note whether they are circuit codes or ratio and performance codes. Circuit codes (P0748, P0753, P0758) mean the module did not see the electrical response it expected, so a harness, connector, solenoid or controller problem is likely. Ratio codes can just as easily come from low solenoid feed pressure in a worn valve body. Check resistance through the case connector before ordering. Our EPC solenoid symptoms guide has the current and pressure numbers, and the Express van problems guide covers the faults that show up most on these vans. One caution from the trade press: shops have replaced the harness and solenoids on a 2007 Express 3500 and still seen P0753 and P0758 come back, so check the wiring outside the transmission as well.
Built for 2004 and later GM 4L80E and 4L85E transmissions (RPO MT1 and MN8). The 1991-2003 units use a different internal harness and solenoid layout, and this kit will not plug into them; owners of those years should look at our earlier kits. Check the numbers on your old EPC solenoid (24248892) and harness (24200161) against this kit, or give us your year and VIN and we will confirm it before it ships. Every part we carry for this transmission is listed on the 4L80E shop page.
Drain the fluid, remove the pan, then pull the filter and its seal out of the case bore. Unplug the internal harness at every solenoid and at the pass-through connector, then remove the old harness. Unbolt the A and B shift solenoids and their brackets and slide out the EPC and TCC/PWM solenoids. Install the new parts on fresh, ATF-lubricated O-rings and route the new harness along the same path as the original so it cannot rub on the valve body or pan. On these units one of the three plastic retention tabs on the pass-through connector commonly breaks, so inspect it; a connector that is not held firmly can be pushed into the pan and start leaking. Replace the speed sensor with its seal, install the new filter, fit the pan with the new gasket and torque the bolts evenly. Fill with Dexron VI, check the level hot, clear codes, and road test through 4th and lockup. If the van has clutch slip as well, a 4L80E master rebuild kit fixes the cause the electrical parts cannot, and a spare A and B shift solenoid pair is useful to keep in a fleet van's spares box.
| Transmission | |
| Years | |
| TCC/PWM solenoid | |
| EPC | |
| Shift solenoids | |
| Harness | |
| Speed sensor | |
| Filter / gasket | |
| Condition |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. It is for 2004 and later units. A 2003 truck uses the earlier harness and a different EPC solenoid, so choose one of our 1997-2003 kits, or send us the VIN and we will point you to the right one.
Very often it is the EPC circuit. When the module cannot control the pressure control solenoid it sets P0748 and commands maximum line pressure on purpose, which makes every shift harsh. Check the circuit and connector before assuming the valve body or clutches are bad.
The harness takes the same heat cycles as the solenoids and cracks where it bends. A cracked harness causes intermittent codes that come and go with temperature, and those are easy to blame on a good solenoid. Doing both removes the guesswork.
Dexron VI. Refill after the pan goes back on, start the engine, run it through the ranges and set the level with the fluid at operating temperature.
Clear the stored codes and reset the shift adapts with a scan tool if the controller supports it, then drive through all four gears and a converter lockup so the module relearns shift timing on the new parts.
