How to Install Rock Lights Under a Truck

Rock lights mount under the frame, axles, and body of a truck to throw light down and outward at ground level. On the trail they light up the terrain directly under and around your tires so you can see obstacles, drop-offs, and line choices without a spotter shining a flashlight. Off the trail they make a truck look sharp at shows, in the shop, or parked at a campsite.

Most rock light kits use small, sealed LED pods. They sit low and take a beating from rocks, mud, water, and brush. A good IP rating matters here. Look for pods rated IP67 or IP68 so they can handle full submersion for short periods, not just splash resistance. If you wheel in water crossings or deep mud, that rating is the difference between lights that last and lights you replace every season.

Before you buy or start drilling, check your state and local laws. Some colors and always-on underglow setups are restricted on public roads. Many rock lights are sold for off-road use only. Know the rules where you drive. A quick search for your state's vehicle lighting laws will save you a headache later.

The most common kit sizes are four, six, and eight pods. Four pods give you basic corner coverage. Six lets you add a center pod on each side for better fill along the rocker panels. Eight pods give you full coverage front to back and are the right call on longer trucks or full-size rigs where the wheelbase leaves a dark gap in the middle. If you want to go deeper on this decision, read our guide on how many rock lights you need before you order.

Placement comes down to two goals: protect the pods from direct rock strikes and aim them where the light does the most work. Good mounting spots include the inside face of the frame rails, behind the skid plates, behind the lower control arms, and tucked up behind the rocker panel lip. Avoid mounting directly on the bottom of the frame where a rock will hit them head-on. Angling the pods slightly outward throws light onto the ground beside the truck instead of straight down into the dirt.

On lifted trucks with exposed frame rails you have a lot of options. On stock-height trucks the frame is lower and clearance is tighter, so you may need shorter mounting hardware or to tuck pods behind factory skid plates. Walk under your truck with a flashlight before you order and look for flat, protected surfaces near each corner and along the sides.

Getting everything together before you crawl under the truck saves a lot of back-and-forth. The install is straightforward but you will be working in tight spaces, so having the right tools within arm's reach matters.

On the electrical side, a wiring harness built for rock lights makes the job cleaner and safer than splicing directly into your fuse box. A relay-based harness protects your truck's factory wiring and gives you a clean switched circuit. You will also need a switch inside the cab to control the lights. Pick up a rocker switch or a switch panel that fits your dash or A-pillar. Check out the switch options at Crushin' Off Road to match the style of your build.

For wire routing you will want split loom or corrugated loom to protect the wire runs along the frame. Zip ties, self-tapping screws or bolts with lock nuts for mounting the pods, a drill with appropriate bits, wire stripper, crimping tool, and heat shrink connectors round out the kit. If your rock light kit does not include a harness, grab one separately so you are not improvising the electrical side.

The install breaks into three phases: mounting the pods, routing the wire, and making the electrical connections. Work through them in order and you will end up with a clean, reliable setup. Rushing the wire routing is where most installs go wrong, so take your time on that phase.

Start by dry-fitting all your pods before drilling anything. Hold each pod in its planned location and check that it clears moving suspension parts through the full range of travel. Spin the steering lock to lock with the wheels turned hard both ways. Compress the suspension by hand if you can. A pod that clears at ride height can still get wiped out by a control arm at full droop if you did not check.

Once the pods are mounted and the wire is routed, the electrical connection is the last step. Connect the harness ground to a clean chassis ground point, run the switched power lead to a fused circuit or relay, and connect the harness trigger wire to a switched 12V source so the lights only come on when you want them. Then run the cab wire to your switch. Test everything before you button up the loom and zip tie the final runs.

For a deeper look at the wiring side of this job, the guide on how to wire rock lights to a switch walks through relay wiring and switch panel setup in more detail.

The install is only half the job. Rock lights live in the worst environment on the truck. Mud packs into connectors, water sits in wire loops, and vibration works connections loose over time. A few habits after the install will keep them running season after season.

Dielectric grease in every connector is the single best thing you can do. It keeps moisture out and prevents corrosion at the terminals. Apply it before you make each connection during the install, not as an afterthought. Also make sure every wire run has a drip loop, meaning the wire dips down before it enters a connector so water runs off the wire instead of tracking into the connection.

After your first few trail runs, do a quick inspection. Check that zip ties are still tight, pods have not shifted, and connectors are still seated. Mud and rocks can knock things loose faster than you expect. If a pod stops working, check the connector at that pod first before assuming the pod itself is bad. Most field failures are a loose or corroded connection, not a dead LED. Keep a small field repair kit in the truck so you can fix a connector on the trail without cutting wire.