The OE 3-2 downshift control solenoid for GM 4L60E, 4L65E, and 4L70E transmissions; replaces a stuck or open unit that sets code P0785 and causes a harsh or missing 3-2 downshift.
If your Silverado, Sierra, Tahoe, Yukon or other GM truck with a 4L60E bangs into second when you roll back into the throttle at 30 mph, or the engine flares for a moment before second catches, and the scan tool shows P0785, this is the part most people are searching for. GM 24212327 is the original equipment 3-2 downshift control solenoid used in the 4L60E, 4L65E and 4L70E. It is a single solenoid with a chrome-finished metal body and barb-style ports, about 3.09 x 2.06 x 2.06 inches, and it is the same part the factory installed, so its winding resistance and response are what the PCM is calibrated to expect.
A 3-2 downshift in this transmission is a handoff: the 3-4 clutch has to release while the 2-4 band applies. If the clutch lets go too early the engine flares; if the band grabs before the clutch is released the drivetrain binds and the downshift slams. The 3-2 control solenoid is the PCM's tool for timing that overlap. It meters exhaust from the 3-2 downshift circuit so the release happens at the right rate for the vehicle speed and throttle position. It is fed from the same regulated AFL oil supply as the shift, TCC and pressure control solenoids, and it is not one of the two solenoids that pick the gear. That is why a failed 3-2 solenoid normally leaves the truck with all four gears but a bad downshift.
Measure first. ATRA's 4L60E resistance chart lists the 3-2 control solenoid at case connector pins E and S, with a normal reading of 9 to 14 ohms. A reading that is open or far outside that range points at the solenoid or its internal harness. If P0785 is set together with P0753, P0758 or a TCC code, do not assume several solenoids died at once. ATRA bulletin 1244 traces that pattern to lost voltage on the solenoid power feed at terminal E, often a tired ignition switch or a fuse, and bulletin 583 describes a poor terminal crimp on circuit 1020 doing the same thing. If the circuit checks good and the downshift still binds, the 3-2 control valve spring in the valve body is a known breakage point. Our 3-2 downshift solenoid and P0785 guide walks through the whole test sequence, and the 4L60E shift solenoid symptoms guide covers how the other solenoids fail.
This listing fits the GM 4L60E, 4L65E and 4L70E. That family runs behind 1993-2013 Chevrolet Silverado 1500, Tahoe, Suburban, S10, Blazer, Camaro and Corvette and GMC Sierra 1500, Yukon and Sonoma. GM revised connectors and valve bodies more than once in that span, so compare your old solenoid's body, ports and connector to the photos, or send us your year and VIN and we will confirm before it ships. Everything else for this unit is on the 4L60E parts collection.
The solenoid sits on the valve body, so the job starts with draining the fluid and dropping the pan and filter. Unplug the internal harness lead, then hold the solenoid in with your thumb while you pull its retaining clip. Some of the solenoids on this side are spring loaded, and easing it out slowly keeps the internal valve from dropping into the case passage. Lube the new O-ring with ATF, press the solenoid straight in, refit the clip and reconnect the lead. Install a new filter and pan gasket, refill with Dexron VI, clear codes and road test several 3-2 roll-ins at different speeds. If you are already in the pan on a high-mileage unit, the 4L60E pressure control solenoid is the other wear item that affects shift feel, and the 7-piece master solenoid kit replaces every solenoid at once if the originals are all the same age.
| Fits | GM 4L60E, 4L65E, 4L70E |
| Part number | GM 24212327 (OE) |
| Function | 3-2 downshift control solenoid |
| Fixes code | P0785 |
| Material | Metal, chrome finish |
| Ports | Barb inlet and outlet |
| Dimensions | 3.09 x 2.06 x 2.06 in |
| Quantity | 1 solenoid |
| Ships | From the USA |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It will when the solenoid itself is open, shorted or sticking. Check resistance at case connector pins E and S first; ATRA lists 9 to 14 ohms as normal. If the reading is good, look at the power feed, the harness and the valve body before buying.
All of the solenoids share one power supply at terminal E. ATRA traces multiple solenoid codes and limp mode to lost voltage on that feed, a bad ignition switch, a blown fuse or a poor crimp on circuit 1020. Fix the circuit before replacing parts.
No. Gear selection is done by shift solenoids A and B. The 3-2 solenoid only times the 3-4 clutch release against the 2-4 band apply on the downshift, so a bad one usually leaves all four gears with a harsh or flared 3-2.
Use Dexron VI ATF, which is backward compatible with earlier Dexron specs. Replace the filter and pan gasket while the pan is off.
Clear the codes and road test through several 3-2 downshifts. On models that support adaptive shift learning, resetting the adapts with a scan tool helps the PCM settle in faster.
