Genuine LiftMaster K1A6408 APE assembly — the absolute position encoder on its plastic tray, with the RPM board and mounting hardware, for LiftMaster's 12 V and 24 V DC pad-mount gate operators. The APE is what tells the control board where the gate is: it counts the motor's turns and gives the board an exact position, so there are no mechanical limit switches to drift. When it stops counting cleanly the gate overruns, stops short, loses its limits after a power cut, or the board throws an encoder error.
K1A6408 or a K76 encoder kit? The K1A6408 is the encoder assembly itself — the item in the parts diagram. The K76-34697 (24 V, CSL24 / HCTDCU), K76-34644 (24 V, CSW24 / RSW12) and K76-34697-3 (12 V, RSL12) are LiftMaster's encoder service kits with the harness and hardware for one model. If the sensor alone has failed and your harness is sound, the K1A6408 is the part; if the harness or connector is damaged too, order the kit for your model. Send us a photo of what is on the tray and we will match it.
Specifications
| Part number | K1A6408 (printed on the parts lists as APE Kit, 24V / APS Encoder, 24V) |
|---|---|
| Description | Absolute position encoder assembly: RPM board on plastic tray with mounting hardware |
| Size | About 4 in × 2 in × 3/4 in |
| Fits | LiftMaster CSL24U, CSL24UL, CSL24V, CSL24VDC, CSW24U, CSW24UL, CSW24V, CSW24VDC, RSL12U, RSL12UL, RSL12VDC, RSW12U, RSW12UL, RSW12VDC, HCTDCU, HCTDCUL |
| Condition | Genuine LiftMaster, new |
Operators it fits
| Operator | Parts page | Encoder service kit |
|---|---|---|
| CSL24U, CSL24UL, CSL24V, CSL24VDC slide | CSL24 parts | K76-34697 |
| CSW24U, CSW24UL, CSW24V, CSW24VDC swing | CSW24 parts | K76-34644 |
| RSL12U, RSL12UL, RSL12VDC slide | RSL12 parts | K76-34697-3 |
| RSW12U, RSW12UL, RSW12VDC swing | RSW12 parts | K76-34644 |
| HCTDCU, HCTDCUL overhead / vertical-lift gate | HCTDCU parts | K76-34697 |
Is the encoder actually the problem?
The encoder is one of four things that produce the same symptoms. Work down the list:
| Symptom | Check first |
|---|---|
| Gate overruns the open or close position | The encoder — but first check that the gate is not binding and the batteries are good; a slowing motor confuses the count |
| Stops short and reverses with nothing in the way | Encoder, then the obstruction sensitivity setting |
| Loses its limits after every power cut | Encoder first, then the batteries (a dead battery pack drops the board mid-count) |
| Board shows an encoder / APE error | The encoder harness and connector, then the encoder |
| Runs one way only, no error | The board or the reset switch, not the encoder |
After fitting
Re-learn the limits from scratch — the board has no idea where the gate is with a new encoder — then run a full open and close and the obstruction test. If the count is still erratic, check the batteries under load before you suspect the new part.
Fit surge protection when you fit electronics. An encoder that died in a storm usually took the board with it; a new part on the same unprotected supply is at the same risk.
Related
CSL24 parts · CSW24 parts · RSL12 parts · RSW12 parts · HCTDCU parts · all LiftMaster gate operator parts
Not sure whether you need the assembly or the kit? Send the operator model and a photo of the encoder on its tray to parts@gatehousesupplies.com or call 866-965-5599. We would rather confirm it than have you order twice.
