Wiring Up Your Rough Country MLC 6 Setup
The MLC 6 system from Rough Country is first and foremost a suspension piece - multi-leaf coil springs that replace your stock shackles and add lift. There isn't a dedicated wiring harness that comes with it, which is the first thing most people don't figure out until they're already staring at a bag of hardware and wondering where the fuse goes. You're basically adding height to the truck and then dealing with whatever electronics you want to run at the new ride level. That said, people buying this system usually end up needing wiring help for lights, winches, or auxiliary switches, and that's where things get messy. The lift changes your mounting points, routes your grounds, and often requires you to run new wire paths that didn't exist before. I learned this the hard way on a '15 Silverado - I mounted my LED light bar to the new bumper after the install, ran the power feed through the frame rail, and blew three fuses before realizing my ground strap was picking up noise from the alternator because it was sharing a bolt with the fuel tank strap. Moved the ground to a bare metal spot on the frame near the firewall and everything settled down.
Rough Country Mlc 6 Wiring Diagram
Since there's no single diagram from Rough Country specifically for the MLC 6, you're working off general automotive wiring principles applied to your specific vehicle. Here's what you need to know to get it done without calling it a day halfway through. Start by mapping out your power source. The MLC 6 lifts the front end typically between 4 and 6 inches depending on the configuration, which means your factory wiring routes might now be too short or sitting at an awkward angle. Don't fight it - just run new wire. Use 10-gauge for anything drawing more than 15 amps, 12-gauge for lights and switches, and always use a fuse holder within 18 inches of the battery positive terminal. I've seen too many installs skip the inline fuse because "it'll be fine" and then have a melted harness when a pinched wire shorts out three years later. Your ground is where most problems hide. A lifted truck has more distance between the battery and accessories, so every foot of ground wire adds resistance. Find a clean, painted-metal-free spot on the frame - scrape it down to bare steel with a wire brush or sandpaper, use a star washer under the ring terminal, and torque it down. Don't just bolt it over paint and call it done. I once spent two days troubleshooting flickering fog lights on a client's truck only to find the ground was attached to a powder-coated bracket that measured 4 ohms of resistance. Bare metal makes a real difference.
Route your wires away from moving suspension components. The MLC 6 uses a multi-leaf design that articulates differently than coil springs, so your suspension travel characteristics change. Keep all wiring at least 2 inches away from the spring perch, shackles, and any pinch points that close as the suspension compresses. Use split loom or flex conduit where the wire runs near the frame rails, and zip-tie it every 8 to 10 inches so it doesn't hang down and catch on rocks or debris. If you're running auxiliary switches behind the dash, tap into an existing switch circuit or run a new circuit from the fuse box. Most trucks have an accessory fuse slot in the under-hood box that's switched - meaning it's hot only when the key is on. That's usually fine for lights and fans, but if you need something that stays live like a radar detector or charging port, you'll need to tap directly into the battery through an ATO fuse adapter or run a dedicated circuit from the positive terminal with an appropriate fuse. For the rear of the truck, the MLC 6 doesn't touch the rear suspension on most applications - it's a front-end lift primarily. But if your build includes rear LED light bars or backup cameras, route those wires along the frame rail on the driver side, secure them with plastic clips, and run them through the existing rubber grommet near the fuel door if your truck has one. Avoid drilling new holes in the frame unless absolutely necessary - every hole is a potential rust starting point.
Get the Full Details
The one thing people consistently get wrong is the relay setup. Don't run high-draw accessories like winches or light bars directly through a switch. The switch contacts can't handle the current for long, and they'll melt or arc. Use a relay instead - a standard 40-amp automotive relay costs about two dollars and makes the switch only handle the trigger side. Wire the relay so battery power goes directly to the relay terminal 30, the switched output goes to terminal 87, the switch triggers terminal 85, and terminal 86 gets ground. Terminal 87b is normally closed if you need a fail-safe configuration, but for most lighting installs you don't need it. When testing, measure voltage at the accessory with the circuit loaded - meaning the light or winch is actually running. A multimeter reading 12.6 volts with nothing connected doesn't tell you much. You want to see at least 12 volts under load. Anything below that and you've got resistance somewhere in your circuit, usually at a connection point or a long stretch of undersized wire. I'd also recommend labeling every wire at both ends with a piece of electrical tape and a marker before you finish up. Write what it is and where it goes - "TAIL LIGHT R" or "WINCH PWR" or whatever. Six months from now when something acts up, you'll thank yourself. I've pulled apart half a dash on trucks where nobody labeled a single wire and it was pure guesswork.
If you're dealing with a specific accessory that came with Rough Country - like their air compressor kits or light bundles - those usually include their own wiring diagrams. Check the manual for the accessory itself rather than looking for something tied to the MLC 6 specifically, since the lift kit doesn't control or integrate with any electronics. It's purely mechanical. For reference wiring layouts, the general pattern across most trucks follows the same rules regardless of make or model. Fuse to relay to switch to ground for the trigger side, and battery to relay to accessory to ground for the power side. Cross-reference your vehicle's fuse diagram - usually located on the inside of the fuse box cover or in the owner's manual - to find your available circuits and amperage limits. Don't put a 30-amp accessory on a 10-amp fuse and expect it to work.
