Liftmaster LA400 LA400DC LA400U LA400UL Parts

LiftMaster LA400 Swing Gate Operator Replacement Parts

Genuine replacement parts for the LiftMaster LA400 residential DC swing gate operator — primary and secondary actuator arms, control boards, control boxes, brackets and wiring. The LA400 is the 24 VDC mains-powered arm with battery backup, rated to 16 ft or 850 lb per leaf. If you know it as an LA400 gate opener rather than an operator, it is the same unit.

Which LA-series operator do you have? The arms are not interchangeable — check the control box label before ordering.

Model	Voltage	Power	Parts
LA400	24 VDC	Mains, battery backup	This page
LA412	12 VDC	Solar	LA412 parts
LA500	24 VDC	Mains, heavier leaves	LA500 parts

A 24 VDC LA400 arm will not run from a 12 VDC LA412 control box, and the reverse is also true.

Installation manual: LiftMaster LA400 Installation Manual (PDF) — covers installation, limit and force adjustment, remote programming, diagnostic codes and the full troubleshooting chart.

Arms and release hardware

Part Number	Description
041ASWG-0440SA	Spare manual release shaft
LA400DC	Primary 24 VDC actuator arm, arm only — single gate, or the first leaf of a dual
LA400DCS	Secondary 24 VDC actuator arm — second leaf of a dual gate, long lead

Control boards, boxes and chips

Part Number	Description
K001A6039	Control board — original LA400 metal box
K1D8388-1CC	Control board — current LA400 board
K-127A0071E	Chip, V1.6, LA400
K74-36798-5	Control box, plastic — LA400U
K74-39307-2	Control box, plastic — LA400UL
LA400CONTUL	Complete control box with circuit board
XLSOLARCONTUL	XL metal solar control box — larger battery bank

Wiring, switches and brackets

Part Number	Description
K77-19130	Hardware kit
K77-19130-1	Two-post bracket kit — LA400 and LA412
K94-36408-2	Reset switch with product ID resistor
LA400CONTDC	Secondary arm board connector — wired dual gates
LA400-JB40	Junction box with cable

Complete systems

Part Number	Description
LA400PKGUL	Single swing gate operator kit — one arm, up to 16 ft / 850 lb
LA400PKGUL-DUAL	Dual swing gate operator kit — two arms
LA400XL20W	20 W XL solar package

Common faults and the parts involved

Symptoms below are taken from the troubleshooting chart in the LiftMaster LA400 manual (pages 38–40). Work through the chart before replacing anything — the parts listed are the ones most often involved, not a diagnosis.

Symptom	Parts commonly involved
Operator does not run and the error code display is not on	Control board, control box
Control board powers up, but the motor does not run	Actuator arm, secondary arm board connector
Arm moves, but correct limits cannot be set	Reset switch, control board
Gate stops during travel and reverses immediately	Entrapment protection devices, arm
On a dual-gate system, the wrong gate opens or closes first	Secondary arm board connector, junction box
Gate opens, but will not close with a transmitter or Timer-to-Close	Entrapment protection devices, control board

Not sure which arm generation or control box you have? Send a photo of the arm label and the control box to parts@gatehousesupplies.com or call 866-965-5599. We would rather confirm it than have you order twice.