A and B shift solenoid pair for the GM 4L80E and 4L85E, timing the 1-2 and 2-3 shifts; replaces AC Delco 24230289 and 24230288. Cures P0753/P0758.
If your Silverado or Sierra 2500, Suburban, Express or Savana pulls away in 2nd, revs out with no 3rd or 4th, or launches hard and then seems to skip straight to overdrive, the two on/off shift solenoids in its 4L80E or 4L85E are the first suspects. This pair replaces AC Delco 24230288 (solenoid A, the 1-2) and 24230289 (solenoid B, the 2-3). At this price there is little reason to change only one: both coils have the same heat cycles on them, and both come out of the same pan drop.
A 4L80E makes all four forward gears from just these two solenoids. The module switches them in combination: 1st is A on and B off, 2nd is both off, 3rd is A off and B on, and 4th is both on. Each solenoid routes oil to the shift valves when it is energized, so the gear the truck ends up in is decided entirely by which coil is working. That is also why one bad solenoid never costs you a single gear. It costs you two, and the remaining pair looks random until you compare it with that chart.
Separate electrical codes from performance codes. P0753 and P0758 mean the module did not see the voltage change it expected; P0751 and P0756 mean the circuit worked but the gear ratio came back wrong, which points at hydraulics as often as at the solenoid. Then check power. Both shift solenoids and the TCC solenoid share one ignition feed at terminal E of the case connector, so a test light at E with the key on comes before anything else. One Transmission Digest case on a 2007 Express 3500 kept setting P0753 and P0758 after a new transmission, harness and solenoids, and the real fault was a failing ignition switch on that shared feed. With the harness unplugged, each solenoid should read 18-24 ohms, and the two should read close to each other. Our 4L80E shift solenoid guide has the full test sequence, and the Silverado 2500 shift problems guide covers the truck-side faults.
This pair is listed for the GM 4L80E and 4L85E (MT1) used in 1991-and-later heavy-duty Chevrolet and GMC pickups, Suburbans and vans. The 4L80E shift solenoids went through three color-coded designs in the early years, and the later design is approved for any model year, so the number on your old part may differ from the two above. Compare the body shape, the connector and the mounting before installing, or send us your year and VIN. The rest of the electrical and hard parts for this unit are on the 4L80E collection page.
Both solenoids are reached by draining the fluid, dropping the pan and pulling the filter; no teardown is needed. Inspect the case pass-through connector while you are in there, since its plastic retention tabs are known to break and let the connector push into the pan. Remove each solenoid, check the bore for debris, fit the new O-rings lubricated with ATF and seat the solenoid by hand before tightening the retainer. Refill with Dexron VI, clear codes and command each solenoid with a scan tool, listening for a click on and a clack off. If the old pair failed with high mileage on the unit, the EPC and TCC solenoids are the same age; the 4-piece 4L80E solenoid kit covers all of them, and a valve body check ball kit is worth having if the valve body comes off.
| Fits | GM 4L80E, 4L85E (MT1) |
| Replaces | AC Delco 24230289, 24230288 |
| Function | A & B on-off shift solenoids (1-2 and 2-3) |
| Pieces | 2-piece solenoid set |
| Body material | Aluminum alloy |
| Common codes | P0753, P0758 |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Solenoid A is the 1-2 shift solenoid and replaces 24230288. Solenoid B is the 2-3 shift solenoid and replaces 24230289. Note which position each old one came from before you remove them.
That pattern matches solenoid A stuck off. Before you buy, confirm power at terminal E of the case connector, because a lost feed to both solenoids also leaves the truck in 2nd.
Yes, the listing covers both the 4L80E and the 4L85E. Compare the connector and body with your old parts or send us your year and VIN if you are unsure.
Not required. If the transmission has high miles and the other solenoids have never been replaced, doing all four in one pan drop with a full solenoid kit usually saves time and money.
Refill with Dexron VI and check the level hot. Clear codes and road test through all four gears; the module adapts shift feel over the next several drive cycles.
