Complete Truck Rock Light Installation Guide: Tools Preparation & Step-by-Step Instructions｜BLIAUTO 2025 Professional Guide

I. What Are Rock Lights, and Why Install Them?

Rock lights are small LED lamps installed under the vehicle chassis, facing the ground or wheel wells. Their main purposes include:

Illuminating ground obstacles (rocks, pits, roots) during off-road driving, improving safety and passability;

Serving as display/ambient lights at campsites or auto shows (static scenarios);

Acting as auxiliary lighting, making it easier to check tires and the chassis at night.

Note: Rock lights are usually permitted on private land, off-road trails, or for static display, but their use on public roads is restricted (see regulations section).

II. Preparation Before Installation—Tools and Materials Checklist

Essential Tools:

Electric drill, impact driver (with self-tapping screw kit)

Wrench set, box/Allen wrenches

Wire stripper, crimping pliers, multimeter

Heat shrink tubing, electrical tape, waterproof connectors (IP67/IP68 recommended)

Zip ties, gaskets/anti-vibration pads

Wire loom/conduit (to protect wiring)

Anti-rust paint or primer (for post-drilling protection if needed)

Materials:

Certified rock lights (preferably with waterproof rating, durability rating, and aluminum heat dissipation housing)

Waterproof wiring harness (with relay and fuse holder)

Relay (commonly 12V 40A), fuses (matched to lamp wattage), switch (preferably with indicator light)

Ground wire (thick copper), terminals, heat shrink sleeves

Lighting Selection Tip: Choose lights with heat sinks, solid epoxy sealing, clear rated voltage/wattage, and waterproof/shock-resistant certification. If you plan to use them on public roads as auxiliary lights, prioritize products certified with DOT / E-Mark / ECE / ADR to reduce compliance risks.

III. Pre-Installation Checks (Safety & Compliance)

Confirm Usage: Off-road or static display only? If considering short use on public roads (not recommended), check local regulations and lamp certification.

Electrical System Check: Calculate total power consumption and confirm the truck’s battery and alternator can handle the load. For higher demand, consider auxiliary power or additional fuses/relays.

Position Planning: Choose positions shielded from direct rock impact (wheel wells, near control arms, behind bumpers), and ensure they don’t interfere with steering or braking systems.

Heat Dissipation & Waterproofing: Lamps and wiring must be adequately sealed and cooled to prevent shorts after prolonged water immersion.

IV. Step-by-Step Installation Guide

Step 1—Design & Marking

Park the truck on level ground, engage the handbrake, and disconnect the negative battery terminal.

Based on lamp size and beam angle, mark mounting positions under the chassis, leaving inspection space and cable tie routes.

Step 2—Drilling & Mounting (if required)

Drill pilot holes, then expand to size; sand edges and coat with rust-prevention paint.

Use anti-vibration pads between the lamp housing and chassis; secure with stainless steel screws and lock washers.

Step 3—Wiring (Core Principles)

Keep wiring away from heat, moving parts, and sharp edges; protect with loom or conduit.

Route the main power wire from the engine bay or battery, using a relay to control power (coil triggered by switch or ignition ACC).

Install a fuse close to the battery (capacity = total wattage ÷ 12V, rounded up).

Ensure solid grounding: strip paint at contact point, and attach ring terminal with self-tapping screw.

Simplified Wiring Diagram:

Battery (+) → Fuse → Relay terminal 30 → Rock light positive

Relay terminal 87 → Lamps

Relay coil 85 → Switch (or ignition ACC) → Fuse/indicator → Switch ground

Relay coil 86 → Chassis ground

Lamp negatives → Common grounding point or battery (-)

Step 4—Switch & Control

Install an independent cabin switch (with indicator light), plus a master power cut-off switch to prevent battery drain during long parking.

For RGB, remote, or app control, choose CAN-bus or Bluetooth controllers with automotive-grade protection.

Step 5—Testing & Sealing

Before reconnecting the battery, test continuity with a multimeter. After reconnecting, briefly power on to test all lamps.

Check steering/suspension travel to ensure no interference.

Seal all exposed connections with waterproof silicone, tidy up wiring with zip ties, and secure against abrasion.

V. Common Issues & Troubleshooting

Lights won’t turn on: Check fuse, relay click, switch, and ground.

One side not working: Inspect branch connectors and possible wire breaks.

Switch sparks or overheats: Circuit overloaded or switch underrated → replace switch or use relay.

Flickering or cutting out while driving: Check alternator output, battery health, and grounding.

Shortly after water immersion: Inspect seals and connectors; upgrade to IP68-rated connectors if needed.

VI. Maintenance Tips

Inspect fasteners, grounding, and insulation every 6 months. After mudding/water crossing, wash and recheck seals.

Re-tighten fasteners after heavy off-roading; use thread-locker if needed.

Dimming light output usually indicates heat or driver failure; clean, repair, or replace as required.

VII. Key Regulations by Country/Region (Overview, Not Exhaustive)

United States: No federal ban, but most states classify underglow/rock lights as “off-road use only.” On-road use is restricted, especially for flashing, red, or blue lights resembling emergency vehicles. Best practice: keep them off when returning to public roads. Some states have stricter rules on color and flashing.

Europe/UK: Additional lamps must comply with UNECE/ECE standards and bear an E-mark (e.g., E11, E9). Non-certified lights may be illegal on public roads. Beam intensity, placement, and cumulative output are regulated. Static/off-road displays are more flexible, but certified products are recommended.

Australia: Governed by ADR (Australian Design Rules), which regulate lamp distribution and color (e.g., ADR 87/00). States may add restrictions, particularly on colors and public-road use. Always check local state transport authority rules.

Canada: Provincial rules vary. Some provinces allow static, non-flashing underglow but prohibit flashing red/blue. Others ban certain colors entirely for road use. Always confirm provincial regulations.

Other Regions: Most countries ban lights that resemble emergency signals (red/blue flashing) or cause glare. Check before international travel.

Summary: Rock lights are usually legal to install but often restricted for use on public roads. Colors (red/blue/flashing), brightness, and certification (ECE/DOT/ADR) determine compliance. Install switches or covers to disable them when required.

VIII. FAQ

Q: Can rock lights be used as driving lights?

A: Not recommended. Their beam is aimed at the ground and does not meet road headlamp beam pattern standards. Use certified headlamps/fog lamps for road driving.

Q: Are colors restricted? Can I install RGB?

A: RGB is fine for private property or shows, but many jurisdictions ban red/blue (emergency vehicle imitation) and flashing effects. Some even restrict green or other colors. Always turn them off before entering public roads.

Q: Will rock lights affect vehicle inspections?

A: If uncertified or altering OEM lighting, they may fail inspection. Keep wiring reversible and use switches/covers for compliance.

Q: Will DIY installation void my warranty?

A: If installation damages the chassis or wiring, the warranty may be affected. Minimize modifications or use professional installers.

IX. BLIAUTO Expert Tips

Frequent off-roaders should choose shockproof, waterproof, and heat-dissipating designs (aluminum housing + silicone sealing).

Use independent relays and fuses, and add a master cutoff switch near the engine bay to prevent parasitic drain.

Route wires with zip ties and padding to avoid contact with brake/fuel lines.

Double-seal joints with crimp connectors and heat shrink for maximum waterproofing.

X. Conclusion

Rock lights significantly improve ground visibility during off-road driving and add visual appeal at campsites or shows. However, electrical safety and legal compliance are critical. Always choose certified products, wire correctly, and disable non-compliant lights on public roads.

At BLIAUTO, we can provide custom rock light installation plans tailored to your truck model (including lamp recommendations, wiring diagrams, and parts list). Contact us with your truck details and intended use!