LiftMaster LA400DC Primary Arm – 24VDC Replacement Linear Actuator (Arm Only)
The LiftMaster LA400DC Primary Arm is the genuine OEM replacement linear actuator arm for LA400 single swing gate operators. This is the arm only — it does not include the control box, receiver, or safety sensors.
Ideal for replacing a failed or worn-out actuator on an existing LA400 system without buying a complete new operator kit. Saves time and money for installers and property owners.
Need the complete operator? See the LA400 single-gate kit. Building a dual gate? You'll also need the LA400DCS secondary arm, or start with the LA400 dual kit.
Key Features
- 24VDC linear actuator – smooth, quiet soft start and stop operation
- Designed specifically for LiftMaster LA400 gate systems
- Includes 6 ft cable and basic mounting hardware kit (K77-19130)
- MyQ® compatible when paired with a compatible LA400 control board
- Durable construction for residential and light commercial use
- Updated modern design (new style since August 2014)
What's Included
- LA400DC primary actuator arm
- 6 ft pre-wired cable
- Basic mounting hardware kit (K77-19130)
Important: This is a replacement arm only. A working LA400 control box and receiver are required for operation.
Primary or Secondary Arm?
| Your situation | Order this |
|---|---|
| Replacing the arm on a single gate | This arm — LA400DC primary |
| Replacing the second arm on a dual gate | LA400DCS secondary arm |
| Adding a second leaf to a single system | LA400DCS secondary arm |
| Control box has failed too | LA400CONTUL control box, or a complete kit |
Compatibility
Designed for:
- LiftMaster LA400 single swing gate operators
- LA400PKGUL and LA400UL complete operator kits
- Existing LA400 installations needing arm replacement
Note: For dual-gate systems you need one primary arm (this model) plus one secondary arm (LA400DCS).
Manuals, Diagrams & Parts
Download the LA400DC Installation Manual (PDF) — mounting, wiring and limit setup for the arm.
Download the full LA400 Operator Manual (PDF) — complete programming and error code list.
LA400 parts breakdown diagram · All LA400 replacement parts
LiftMaster LA400 Error Codes & Troubleshooting
Quick reference for common diagnostic codes when troubleshooting the LA400 system. Codes 32, 33, 91, 92, 93 and 94 are the ones that usually point at the arm itself.
| Code | Description / Solution |
|---|---|
| 31 | Main control board failure – disconnect power for 15 seconds and reboot; replace the board if it persists |
| 32 / 33 | Linear drive disengaged, Arm 1 / Arm 2 – re-engage the arm and check wiring |
| 34 | Absolute position encoder error – check cable connections, then reprogram the limits |
| 35 | Max run time exceeded – check for an obstruction and reprogram the limits |
| 38 / 39 | Hard stop limit – limit set too tight or the arm is at end of travel; re-adjust |
| 51 / 52 | Pass-point not detected – check the yellow pass-point wiring, reprogram limits |
| 60 | Minimum monitored entrapment devices not installed |
| 91 / 92 | Force reversal – check for an obstruction and that the arm moves freely |
| 93 / 94 | RPM or stall reversal – check wiring and arm engagement; a failing arm often shows here |
| 99 | Normal operation |
The complete error code list and detailed troubleshooting is in the operator manual linked above.
Why Choose the LA400DC Replacement Arm?
- Cost-effective way to repair instead of replacing the entire operator
- Direct OEM fit – no modifications required
- Restores smooth, quiet gate operation
- Ideal for service professionals and gate companies
- Extends the life of your existing LA400 system
Product Summary
LiftMaster LA400DC Primary Arm – official 24VDC replacement linear actuator arm, arm only, for LA400 single swing gate operators. Includes a 6 ft cable and hardware, MyQ compatible. The fastest and most economical way to repair a failed LA400 gate arm.
