Mount the electric jack to the A-frame with three bolts (15-20 ft-lb), connect the positive wire to the 12V battery via a 30-amp fuse, and ground the black wire to the frame.
Replacing a worn-out manual tongue jack with an electric unit is one of the best upgrades you can make for your trailer or RV. It eliminates the manual cranking that makes hitching up a chore, especially on uneven ground or in bad weather. If you haven’t picked a replacement yet, our roundup of the best electric trailer jacks for your rig will help you find the right model for your trailer weight and budget. The installation process itself breaks down into three stages: safely supporting the trailer, bolting the new jack into place, and wiring it to the 12V system.
Tools and Preparation for the Job
Park the trailer on level ground and chock the wheels securely. Never rely on the tongue jack alone to support the trailer while you work. Use jack stands placed under the trailer frame, or keep the trailer firmly hitched to the tow vehicle. Disconnect the trailer battery or the existing jack’s wiring before you start any electrical work to eliminate the risk of a short circuit.
Gather the tools and parts you will need:
- 9/16-inch socket or combination wrench
- Torque wrench capable of 15-20 ft-lb
- Penetrating oil for rusty fasteners
- Wire strippers and heat-shrink butt connectors
- 30-amp inline fuse holder (if your jack does not have integrated circuit protection)
- Lower support plate kit (if your trailer’s A-frame lacks one)
Having everything on hand before you start makes the swap much smoother.
How to Mount the Electric Trailer Jack
Remove the foot or wheel from the old jack first, then remove the three mounting bolts. If they are rusted, apply penetrating oil and work them loose slowly to avoid snapping them off. Lift the old jack out and clean the mounting surface on the trailer’s A-frame thoroughly with a wire brush.
Set the new electric trailer jack into the existing opening or onto the mounting plate. If your trailer lacks a lower support plate, you must install one now—it prevents the jack from punching through the tongue channel under heavy loads. Orient the control panel outward for easy access from the side of the trailer.
Insert the new bolts and tighten them evenly by hand. Finish the job with a torque wrench set to 15 to 20 foot-pounds, as specified in eTrailer’s installation FAQ. Overtightening can distort the jack housing or strip the threads, so stick to the spec.
| Component | Specification | Installation Note |
|---|---|---|
| Mounting Bolts | Three, 9/16-inch head | Torque to 15–20 ft-lb |
| Circuit Protection | 30-amp fuse | Mount fuse holder outside the battery box |
| Power Wire (Positive) | 12 AWG minimum | Route directly to battery positive terminal |
| Ground Wire (Negative) | Black wire | Frame ground or battery negative per jack type |
| Support Plate | Required if absent | Prevents structural damage to A-frame |
Wiring Your 12V Electric Tongue Jack Safely
Wiring an electric tongue jack is a straightforward 12V DC circuit, but the grounding method varies by manufacturer. Run the positive (usually red) wire from the jack to the battery positive terminal, placing a 30-amp fuse as close to the battery as possible.
Connect the negative (usually black) wire according to the jack’s instructions. Some jacks require a dedicated ground wire to the battery’s negative terminal or a clean, rust-free spot on the trailer frame. Others are internally grounded and only need the positive lead connected.
Use heat-shrink butt connectors or ring terminals for all connections to resist corrosion. Secure the wiring along the frame with zip ties to prevent rubbing, pinching, or dragging on the road. Once wired, test the jack by fully extending and retracting it a few times before loading the tongue weight onto it.
Listen for unusual sounds during the test cycle and verify that the automatic stop function works correctly at both full extension and retraction. Once everything checks out, lower the trailer tongue onto the jack. You have just completed a clean electric trailer jack installation that will make every campsite setup faster and safer.
FAQs
Can I install an electric trailer jack on any trailer?
Most A-frame trailers with a standard tongue jack mount can accept a replacement electric unit. You need to confirm the new jack’s weight capacity matches your trailer’s tongue weight and that your trailer has a lower support plate or the ability to add one before purchasing.
What happens if I reverse the positive and negative wires?
Reversing the polarity will cause the jack to run in the wrong direction or not run at all. It can also damage the internal circuitry. Always consult the wiring diagram for your specific electric trailer jack model before connecting power to avoid costly mistakes.
Why is my electric trailer jack running slowly?
Slow operation typically indicates a weak battery, corroded electrical connections, or an undersized wire gauge. Verify that the 12V battery is fully charged and that all connections are clean and tight. Long wire runs require thicker wire to prevent voltage drop.
References & Sources
- etrailer. “How to Install an Electric Trailer Jack – Installation FAQs” Covers standard mounting bolt torque specs (15-20 ft-lb), proper wiring sequences, and circuit protection for 12V DC RV tongue jacks.
Mo Maruf
I created WellFizz to bridge the gap between vague wellness advice and actionable solutions. My mission is simple: to decode the research and give you practical tools you can actually use.
Beyond the data, I am a passionate traveler. I believe that stepping away from the screen to explore new environments is essential for mental clarity and physical vitality.