Wiring Electric Trailer Jack To 7 Way Plug

So, you're looking to wire your electric trailer jack directly into your 7-way trailer plug? Excellent. It's a clean, efficient way to power your jack without fumbling with separate batteries or extension cords. This guide assumes you have a basic understanding of automotive electrical systems, including familiarity with crimping, wiring, and basic testing with a multimeter. We'll walk through the process step-by-step, explaining the wiring, safety precautions, and troubleshooting tips.

Understanding the 7-Way Connector

Before diving in, let's quickly review the 7-way connector (also known as a 7-pin connector). This is the standard connector for most trailers, providing connections for running lights, brake lights, turn signals, brakes (if equipped), and auxiliary power. It's crucial to understand the function of each pin. Here's a typical layout (but always verify with your specific connector!):

White: Ground - This provides the return path for all electrical circuits. A solid, reliable ground is critical for proper operation.
Yellow: Left Turn/Stop Light - Powers the left turn signal and brake light on the trailer.
Green: Right Turn/Stop Light - Powers the right turn signal and brake light on the trailer.
Brown: Tail/Running Lights - Powers the tail lights and running lights on the trailer.
Blue: Electric Brakes - Provides power to the trailer's electric brake system. This is typically controlled by a brake controller in the tow vehicle.
Red: Auxiliary/Spare - Often used for charging a trailer battery, powering interior lights, or in our case, the electric trailer jack.
Black: 12V Power - Provides a constant 12V DC power source. This can also be used for charging a trailer battery or powering the electric trailer jack, and is usually connected directly to the tow vehicle's battery, often through a fuse or circuit breaker.

For our project, we'll primarily focus on the White (Ground), Black (12V Power), and potentially the Red (Auxiliary/Spare) wires. The Red or Black wire provide the power supply. The best choice depends on your specific setup and desired functionality. We'll discuss the pros and cons of each.

Choosing Your Power Source: Black vs. Red

The most common question is which wire to use for powering the trailer jack. Here's a breakdown:

Using the Black (12V Power) Wire:

Pros:

Often already wired with a heavier gauge wire, capable of handling the current draw of the jack.
Typically connected directly to the vehicle's battery, ensuring a stable power supply.
May already be fused or have a circuit breaker installed in the tow vehicle.

Cons:

If the vehicle's ignition is off, and you use the jack excessively, you could potentially drain your vehicle's battery.

Using the Red (Auxiliary/Spare) Wire:

Pros:

May be switched with the ignition, preventing accidental battery drain (though this depends on how it's wired in your vehicle).

Cons:

The wiring may be lighter gauge (smaller wire diameter), potentially inadequate for the jack's current draw. Check your tow vehicle's manual and the wire gauge itself.
Less likely to be already fused. You will definitely need to add an inline fuse.
May not supply power unless the ignition is on, depending on the vehicle's wiring.

Recommendation: If the Black wire is appropriately sized and fused, it's generally the preferred choice for simplicity and reliable power. However, if you're concerned about battery drain or the Black wire isn't adequate, the Red wire can be used, provided you address the potential issues of wire gauge and fusing.

Wiring Procedure: Step-by-Step

Safety First! Disconnect the tow vehicle's battery before starting any electrical work. This prevents accidental shorts and potential damage.

Determine the Jack's Wiring: Identify the positive (+) and negative (-) wires on your electric trailer jack. The manual that came with your electric jack will designate these wires. The most common colors are red for positive and black for negative.
Connect the Ground (White) Wire: Connect the negative (-) wire from the jack to the White (Ground) wire in the 7-way connector. Use a high-quality crimp connector, ensuring a secure and tight connection. Consider using a butt connector with heat shrink tubing for added protection against corrosion and moisture.
Important: A poor ground connection is a major cause of electrical problems. Make sure this connection is solid!
Connect the Power Wire (Black or Red): Connect the positive (+) wire from the jack to either the Black (12V Power) or the Red (Auxiliary/Spare) wire in the 7-way connector, based on your decision from the previous section. Again, use a quality crimp connector and heat shrink tubing.
Install an Inline Fuse (If Necessary): If you are using the Red wire, or if the Black wire in your tow vehicle is *not* already fused, you must install an inline fuse near the 7-way connector on the trailer side. The fuse amperage should be slightly higher than the jack's rated amperage draw, but not excessively high. Consult your jack's manual for the recommended fuse size. If the manual is not available, a good rule of thumb is to use a fuse that's about 125% of the jack's rated amperage.
Fusing protects your wiring and the jack from overcurrent damage. Do not skip this step if it's required!
Protect the Connections: Wrap all connections with electrical tape or use heat shrink tubing to protect them from the elements.
Test the Connection: Reconnect the tow vehicle's battery. Connect the 7-way connector to the tow vehicle. Test the electric trailer jack to ensure it's working correctly. If it doesn't work, proceed to the troubleshooting section.
Secure the Wiring: Use zip ties or other fasteners to secure the wiring along the trailer frame, preventing it from dragging or being damaged. Avoid sharp edges that could chafe the wires.

Troubleshooting

If the jack isn't working after wiring, here are some things to check:

Ground Connection: The most common problem. Ensure the ground connection is clean, tight, and properly connected to both the jack and the 7-way connector. Use a multimeter to test for continuity between the jack's negative terminal and the trailer frame.
Fuse: Check the inline fuse (if installed) and the tow vehicle's fuse box for blown fuses related to the trailer wiring.
Voltage: Use a multimeter to check for voltage at the 7-way connector (on the trailer side) between the White (Ground) wire and the Black or Red wire (whichever you used). You should see approximately 12V DC.
Wiring: Double-check all wiring connections to ensure they are secure and properly connected. Look for any signs of damaged or frayed wires.
Jack Functionality: Before you start the wiring process, ensure that your jack is in good working order. Connect the jack directly to a known good battery to ensure it extends and retracts properly.
Tow Vehicle Wiring: Use a 12V test light or multimeter to probe the 7-way connector on the tow vehicle, verifying that the Black and/or Red wire provides voltage when connected. Verify the ground wire is also connected properly in the tow vehicle and not corroded.

Wire Gauge Considerations

The wire gauge (thickness) is crucial for handling the current draw of the electric trailer jack. A wire that's too small can overheat, causing voltage drop and potentially damaging the jack or the wiring. Consult the jack's manual for the recommended wire gauge. If the manual isn't available, a general guideline is to use at least 12-gauge wire for shorter runs (under 10 feet) and 10-gauge wire for longer runs. When in doubt, it's always better to use a heavier gauge wire (smaller number) than necessary.

Final Thoughts

Wiring an electric trailer jack to your 7-way connector is a straightforward process if you follow these steps carefully and pay attention to detail. Remember to prioritize safety, use quality components, and double-check your work. With a little patience and effort, you can enjoy the convenience of a powered trailer jack without the hassle of separate batteries or cords. If you're not comfortable with any of these steps, it's always best to consult a qualified mechanic.