Complete 7-piece 4L80E/4L85E solenoid overhaul for 1997-2003 GM: TCC/PWM, EPC, both shift solenoids, internal harness, filter and pan gasket.
If your 1997-2003 Chevy or GMC 2500/3500, Suburban 2500 or Express/Savana van keeps dropping into limp mode, sets shift solenoid codes that clear and come back, or shudders when the converter locks on the highway, the electrical side of the 4L80E is the first place to look. This 7-piece kit replaces all of it for the 1997-2003 layout in one pan drop: TCC/PWM solenoid 24210864, EPC solenoid 24220158, shift solenoid A 24230288, shift solenoid B 24230289, internal harness 24222798, filter with seal 24210956 and pan gasket 8677743. Every piece is new.
The 4L80E has no throttle cable or governor. The truck's computer decides when to shift and how hard, and the solenoids are how it acts on those decisions. Shift solenoids A and B are on/off valves; the pattern of which one is energized puts the valve body in first, second, third or fourth. The EPC solenoid is a variable force motor that sets line pressure, so it controls how firmly every clutch and band applies. The TCC/PWM solenoid pulses the converter clutch on so lockup feels like a gentle drop in RPM rather than a bump. All four hang off the internal harness, which runs from the case pass-through connector across the valve body. By the 1997-2003 era most of these trucks have well over 150,000 miles of heat cycling on that harness and those coils.
Not every 4L80E shift complaint is electrical. Worn bushings and a worn actuator feed limit valve bore can starve the solenoids of feed oil, and forward or direct clutches worn by heavy towing will slip no matter how good the solenoids are.
Pull codes first and separate circuit codes (the module sees an electrical fault) from performance codes (the circuit checks out but the shift did not happen). For circuit codes, measure each solenoid through the case connector. GM's diagnostic charts for this family of on/off shift solenoids list roughly 19 to 31 ohms; a reading well outside that, or one that changes when you flex the harness, condemns the part or the wiring. Our 4L80E shift solenoid guide walks through the A and B tests, and the EPC solenoid symptoms guide covers line pressure checks. If the truck is a Silverado or Sierra, the Silverado 2500 shift problems guide lists the faults we see most on that platform.
This kit is listed for GM 4L80E and 4L85E transmissions (RPO MT1 and MN8) built 1997 through 2003. That covers the late GMT400 and the first GMT800 2500/3500 pickups and Suburbans, plus Express and Savana heavy vans of those years. GM changed the internal harness and EPC solenoid for 2004, so a 2004-up unit needs a different kit. If your truck sits near a changeover year or has had a replacement transmission installed, compare the numbers on your old EPC solenoid and harness with the ones listed above, or send us the year and VIN and we will confirm the match before it ships. Everything else we stock for this transmission is on the 4L80E parts page.
Drain the fluid and drop the pan. Pull the old filter, making sure the seal comes out of the case bore with it. Unplug the harness from each solenoid and at the pass-through connector, remove the clips and bolts, and lift the old harness and solenoids out. Clean the pan and magnet and look at what was on the magnet: fine gray paste is normal, but metal flakes or friction material means the clutches need attention too. Fit each new solenoid with its O-rings lubed in fresh ATF, then lay the new harness along the original route and clip it so it cannot rub the filter or pan. Check the pass-through connector closely; one of its three plastic retention tabs often breaks, and a loose connector can be pushed into the pan and leak. Install the new filter and pan gasket, snug the pan bolts evenly, and fill with Dexron VI. Clear codes and road test through all four gears and lockup.
If the valve body check balls or the separator plate look worn while the pan is off, the 4L80E check ball kit is a cheap add. When the magnet shows clutch debris, plan for the 4L80E overhaul kit rather than hoping new solenoids will cover a slipping clutch pack.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. This kit is for 1997-2003 units. GM changed the internal harness and the EPC solenoid for 2004, so a 2004 and later truck needs one of our 2004-up kits. Send us the VIN if you are not sure which you have.
You do not have to, and if the B solenoid tests bad and the harness is sound, a single solenoid fixes it. The full kit makes sense on high-mileage trucks where the harness is brittle and the other solenoids have the same miles, because intermittent faults tend to move from one circuit to the next.
Yes. It includes filter 24210956 with its seal and pan gasket 8677743, so the job can be finished without a separate parts run.
Dexron VI. It is the current GM fluid and is approved for use in transmissions that originally called for Dexron III. Check the level hot with the engine running.
Clear the stored codes so you can tell whether anything returns. Then drive through all four gears and a few converter lockups so the computer adapts to the new parts. If codes come back right away, check the wiring outside the transmission as well.
