Roots Dual Headlamp Relay Wiring Kit (H4) – 12V Heavy-Duty Harness with Fuse – Brighter Headlights + Switch Protection (Cars with H4 Bulbs)

Upgrade your headlight wiring the right way. This Roots Dual Headlamp Relay Wiring Kit for H4 bulbs sends direct battery power to the bulbs through a relay + fuse, reducing voltage drop and protecting your combination/headlight switch from overload. Built as a plug-and-play harness for cars running H4 headlamp sockets—ideal when headlights feel dim, wiring heats up, or after bulb upgrades.

Why this kit exists (real problem → real solution)

Many cars with factory wiring send headlamp power through thin OE wiring and the stalk/combination switch. Over time that can lead to:

• Dim headlights even with good bulbs

• Heat at the switch or socket, melting/aging connectors

• Flicker / unstable beam when wiring is tired

• Reduced performance after installing higher output H4 bulbs

This Roots kit solves it by using a relay-based harness that pulls power directly from the battery (with a fuse for safety) and feeds the H4 headlights with more stable voltage—so you get closer to the bulb’s intended brightness and reduce stress on the OE switchgear.

Who should buy this

• Cars with dual headlamps using H4 bulbs/sockets

• Anyone facing dim headlights, weak throw, or switch overheating

• Owners doing a headlight bulb upgrade and want wiring protection

Who should NOT buy this (return-prevention gate)

• If your car does not use H4 sockets (H1/H7/9005 etc.)

• If you have a single headlamp setup requiring a different harness type

• If your issue is a bad reflector/projector alignment (wiring won’t fix optics)

Key Features 

✅ Direct Battery Feed via Relay Harness – steadier current delivery to headlamps
✅ Dual Relay System – designed to handle headlamp load without stressing OE wiring
✅ Inline Fuse Protection – safety layer for the main feed
✅ Protects Headlight/Combination Switch – reduces overheating/overload risk
✅ Plug & Play Style Harness – easier installation with pre-fitted terminals
✅ Best Use Case – old wiring, dim lights, bulb upgrades, highway night driving
✅ OEM-style Upgrade Approach – relay harness is the correct method vs cutting OE wires (trust-builder)

(Notice: I did not claim copper %, relay amp rating, waterproofing, ceramic holders—because your current page doesn’t prove it.)

Technical Specifications 

• Brand: Roots

• System Voltage: 12V

• Bulb/Socket Type: H4 (dual-beam Hi/Lo)

• Application: Dual headlamp wiring relay harness (cars)

• Protection: Inline fuse (included)

• Install Type: Plug & play harness (no complex rewiring)

Compatibility

Fits: Most Indian cars that use H4 headlamp bulbs/sockets. (Verify your headlight connector before ordering.)

Common H4 cars (examples):

• Maruti Suzuki: 800, Alto, Swift, Dzire, WagonR

• Hyundai: i10, i20, Santro, Verna

• Also used across: Tata / Mahindra / Honda / Toyota models that run H4 sockets

Not compatible (common confusion):

• Cars with non-H4 bulb types (H1/H7/H11/9005 etc.)

• Vehicles with fully integrated OE projector/LED modules that don’t use H4 sockets

What’s in the Box

• 1 × Roots Dual Headlamp Relay Wiring Kit (H4, 12V)

• 1 × Inline fuse + wiring harness (as supplied)

Installation Notes 

• Recommended installation by an auto electrician (10–20 minutes typical).

• Check H4 socket behind your headlight before ordering.

• Connect to battery + ground as per harness layout; ensure fuse is seated.

• After install: verify high/low beam switching and aim alignment.

• If your headlight socket is heat-damaged, replace the socket along with harness.

FAQ 

Q1) How do I confirm my car is H4?
Check the headlight bulb type in your owner’s manual or inspect the bulb/connector. This kit is specifically for H4.

Q2) Will this make my headlights brighter?
It can improve brightness by reducing voltage drop and giving the bulb more stable power—especially on older wiring. Results depend on bulb condition and reflector/projector health.

Q3) Does this protect the headlight switch?
Yes—this is one of the main reasons relay harnesses exist: they reduce high-current load through the OE switchgear.

Q4) Can I use it with LED H4 bulbs?
If your LED bulb uses a standard H4 plug, the harness can work. However, flicker/driver issues depend on the LED kit design—wiring harness alone cannot fix a poor-quality LED driver.

Q5) Is any cutting/splicing required?
Your product is positioned as plug & play with pre-fitted terminals, so usually no major cutting is required; an electrician can fit it cleanly.

Q6) My car has only one headlamp unit—should I buy this?
This is a dual headlamp relay kit. Single-headlamp setups may require a different harness layout—confirm before ordering.

Q7) I changed bulbs but still dim—why?
Possible causes: reflector burn, lens haze, poor grounding, weak battery, or wrong bulb fitment. Relay kit helps voltage delivery but cannot fix optics.