How to Wire a 12V Winch (With Free PDF Diagram)
Wiring a winch can seem daunting, especially with inconsistent diagrams and generic guides. So we’ve created a clean, easy-to-follow 12V winch wiring diagram (PDF below), based on our PDX MK4 winch. Whether you’re installing for the first time or troubleshooting your control box, this guide will walk you through it.
📊 Download the Wiring Diagram
Click here to download the Ultra Winch wiring diagram (PDF)
🔧 What You’ll Need
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Ultra Winch PDX MK4 (9500lb or 12000lb)
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Supplied Control Box, Wiring Harness, Wired & Wireless Controls
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Optional: PDX MK4 Control Box (if retrofitting to another winch)
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Isolator switch
✅ Recommended Wiring Sequence (Safe + Professional)
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Mount the winch to the bull bar or cradle.
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Install the control box in a secure location, close to the winch motor.
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Connect the signal wires:
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F1, F2, A from the control box to the winch motor terminals.
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Connect the ground (black) wire:
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From control box to battery negative terminal or solid chassis ground.
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Connect the isolator switch:
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Wire the 12V positive output from the isolator to the red input on the control box.
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Ensure the switch is in the OFF position.
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Connect the main positive (red) cable:
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From isolator input to the battery positive terminal.
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⚠️ Why Positive Goes Last
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Prevents accidental sparks or activation during setup.
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Ensures the isolator can stay OFF during all wiring steps.
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The system is fully dead until you choose to power it.
🛠 Optional Final Step
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Test with isolator ON, then activate your wired or wireless controller to confirm operation.
⚠️ Safety Tips When Wiring a Winch
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Do not confuse the motor terminals (A1, F1, F2) with battery terminals.
While A1 (often red) and F2 (often black) may appear colour-coded, these are not positive or negative battery connections. They are motor signal terminals only. -
Never connect F1, F2, or A1 directly to battery power.
These wires control motor direction via the solenoid — incorrect wiring can cause short circuits or motor damage. -
The negative cable from the back of the motor housing must connect directly to the battery negative or a solid chassis ground. This completes the main current path.
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Always ensure the isolator switch is OFF before connecting power cables.
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If in doubt, refer to our wiring diagram and install video for guidance.
🔄 Control Box Compatibility
The Ultra Winch PDX MK4 Control Box is compatible with:
✅ Any 12V DC winch that uses F1 / F2 / A terminals to control motor direction.
That includes most full-size 4x4 winches from major brands.
Simply match the F1, F2, and A terminals to your motor, and connect the included isolator and control wiring as shown.
🚫 Not Compatible With:
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Basic ATV or compact winches that only have two terminals on the motor (positive and negative power inputs).
These do not use directional switching through a solenoid, and will not work with the PDX MK4 control box.
✅ Need to replace your old winch control box and wiring?
The Ultra Winch PDX MK4 Control Box is available separately and can modernise most standard 4x4 winches with safer, sealed switching and plug-in controller support.
View Control Box Product Page
