“Just a bulb, I’ll replace it”—₹500 becomes ₹8,000 when you discover it’s not the bulb, it’s the wiring harness.
Lights aren’t cosmetic—they’re legal requirements and safety essentials. Non-functional brake lights cause rear-end collisions. Dim headlights reduce visibility. Failed indicators confuse other drivers. Sellers dismiss light issues as “minor,” hiding expensive electrical problems: corroded connectors (₹3,000-8,000), ballast failure (₹8,000-15,000), or water damage to light assemblies (₹12,000-30,000).
The trap: Seller says “just needs a bulb.” You replace bulb, problem persists, discover ₹10,000 wiring repair needed.
What you’ll learn:
- Complete light function test checklist
- HID/LED vs halogen (conversion issues)
- Condensation detection (water damage)
- Electrical diagnosis (bulb vs wiring vs module)
- Replacement costs (₹2,000-30,000 per assembly)
Section 1: Complete Light Function Test
Headlights:
- Low beam (both sides)
- High beam (both sides)
- DRL (Daytime Running Lights, if equipped)
Fog lights:
- Front fog lights (if equipped)
- Rear fog lights (if equipped)
Turn signals:
- Front left, front right
- Rear left, rear right
- Side repeaters (on mirrors or fenders)
- Dashboard indicator (should blink at normal rate)
Brake lights:
- Critical test: Have someone press brake pedal while you observe rear
- Both brake lights must illuminate
- Third brake light (high-mount stop lamp)
Reverse lights:
- Engage reverse gear
- White lights on rear should illuminate
Hazard lights:
- Activate hazard button
- All 4 turn signals should blink simultaneously
Interior lights:
- Dome light
- Door courtesy lights
- Vanity mirror lights
- Footwell lights (if equipped)
License plate light:
- Check rear plate illumination
Section 2: Common Light Failures
Failure 1: Non-functional bulb
Symptoms: One light out, others work
Cause: Burnt bulb
Cost: ₹200-1,500 (depending on bulb type)
Easy fix—acceptable
Failure 2: Both headlights dim or non-functional
Symptoms: Both sides equally affected
Cause:
- Wiring issue
- Relay failure
- Switch failure
Cost: ₹2,000-8,000
Failure 3: Fast-blinking turn signal
Symptoms: Indicator blinks faster than normal
Cause: One turn signal bulb burnt (increased blink rate is warning)
Cost: ₹200-800 (bulb replacement)
Failure 4: Moisture/condensation inside headlight
Symptoms: Water droplets or fog inside lens
Cause: Seal failure (crack in housing or vent blocked)
Problem:
- Water corrodes reflector (₹5,000-15,000 to replace housing)
- Water damages bulb connector (₹2,000-5,000 wiring repair)
Indicates: Possible front-end impact, poor-quality housing (aftermarket)
Cost: ₹8,000-25,000 (housing replacement)
Failure 5: HID/LED ballast or driver failure
Symptoms:
- One HID/LED not working (bulb is fine)
- Flickering
- Delayed start
Cause: Ballast (HID) or LED driver module failed
Cost: ₹6,000-15,000 per side
Section 3: HID and LED Conversions (Aftermarket)
Factory HID/LED vs aftermarket conversion:
Factory-equipped:
- Proper projector housing (focused beam)
- Correct ballasts/drivers
- Auto-leveling (to prevent blinding oncoming traffic)
Aftermarket conversion (common seller mod):
- HID/LED bulbs installed in halogen housings
- Problem: Scattered light (blinds others, reduces your visibility)
- Illegal: Not type-approved
- Cost to revert to halogen: ₹1,500-4,000
How to detect:
1. Check housing:
- Projector lens: Likely factory HID/LED
- Reflector housing: If HID/LED bulbs present = aftermarket conversion
2. Beam pattern:
- During test drive at night: Do oncoming drivers flash you?
- Indicates: Your lights blinding them (improper conversion)
Decision:
- If aftermarket HID in reflector housing: Demand reversion to halogen OR ₹5,000 discount
Section 4: Light Housing Condition
Visual inspection:
1. Lens clarity:
- Normal: Clear, transparent
- Problem: Yellowed, hazy (UV degradation)
- Can be polished: ₹1,000-2,500
- If severely damaged: Replace (₹8,000-25,000 per headlight)
2. Cracks:
- Any crack in lens = water entry risk
- Replace: ₹8,000-25,000
3. Aftermarket housings:
- OEM: Manufacturer logo, perfect fit
- Aftermarket: Generic, may have fitment issues (gaps, rattles)
- Indicates: Previous accident (headlight replaced)
4. Alignment:
- Headlights should point straight
- Misaligned: Caused by impact or poor installation after replacement
- Re-alignment: ₹1,000-2,000 (if adjustable)
Section 5: Electrical Diagnosis
If light not working:
Step 1: Check bulb
- Remove and inspect
- Burnt filament: Replace bulb
- Bulb intact: Proceed to Step 2
Step 2: Check fuse
- Locate fuse box (under dashboard or under hood)
- Find corresponding fuse (owner’s manual shows diagram)
- Blown fuse: Replace (₹50-200)
- Fuse intact: Proceed to Step 3
Step 3: Check connector
- Bulb connector: Look for corrosion, burnt terminals
- Corroded: Clean or replace (₹500-2,000)
- Clean: Proceed to Step 4
Step 4: Check wiring/module
- Requires multimeter (voltage test)
- If no voltage at bulb socket: Wiring issue or module failure
- Diagnosis: ₹1,000-3,000 (shop labor)
- Repair: ₹3,000-15,000 (depending on issue)
Section 6: Legal Requirements
Motor Vehicles Act (India):
Mandatory functional lights:
- Headlights (low and high beam)
- Tail lights
- Brake lights
- Turn signals (all 4)
- License plate light
- Reverse light
Non-functional = traffic violation:
- Fine: ₹500-1,000
- Vehicle impoundment possible (severe cases)
If buying car with non-functional lights:
- Demand: Seller fixes before purchase
- Or: Negotiate repair cost discount
Section 7: Real Case – The “Simple Bulb”
2018 Hyundai i20, 55,000 km, asking ₹7,20,000
Test drive (daytime):
- All lights appeared to work
Buyer’s detailed check:
- Right low beam: Not working
- Seller: “Oh, just needs a new bulb, I’ll throw in a bulb for free”
Buyer insisted on diagnosing:
Removed bulb:
- Bulb intact (filament not burnt)
- Not a bulb issue
Checked connector:
- Connector had green corrosion
- Terminals burnt (black marks)
Diagnosis: Connector failure (likely from water intrusion via condensation)
Looked at headlight housing:
- Right headlight had condensation (moisture visible inside)
- Indicates: Seal failure
Repair needed:
- New headlight housing: ₹12,000 (OEM)
- Or: Repair seal + connector: ₹4,000-6,000 (temporary fix, may recur)
Seller’s reaction:
- “I didn’t know it was that serious”
Negotiation:
- Buyer demanded ₹12,000 discount (housing replacement)
- Seller agreed to ₹10,000 off
Final price: ₹7,10,000
Lesson: “Just a bulb” often isn’t just a bulb. Diagnose before buying.
Conclusion: Lights Are Life-Savers
Every light serves a purpose: your visibility, others’ ability to see you, and legal compliance.
Your protocol:
Function test (10 minutes):
- Test every light (see checklist in Section 1)
- Have helper for brake lights, turn signals
Visual inspection (5 minutes):
- Check for condensation, cracks, yellowing
- Verify OEM vs aftermarket housings
Diagnosis (if failure, 5 minutes):
- Check bulb, fuse, connector
Decision framework:
- All lights functional, clear housings: Proceed
- 1-2 burnt bulbs: Negotiate ₹500-1,000 discount (minor)
- Condensation in housing: Negotiate ₹10,000-15,000 discount OR demand replacement
- HID conversion in reflector housing: Demand reversion OR ₹5,000 discount
- Multiple electrical issues: Negotiate ₹15,000-25,000 OR walk away
Lights keep you seen and safe. Don’t drive in the dark.
Key Takeaways
✓ Condensation = seal failure (₹8-25K housing replacement)
✓ Fast-blinking indicator = burnt turn signal (₹200-800 bulb)
✓ HID in reflector housing = illegal + blinds others (revert to halogen)
✓ Ballast/LED driver failure = ₹6-15K (not just bulb issue)
✓ Non-functional brake lights = rear-end collision risk (legal mandate)
✓ Yellowed headlights = polishable (₹1-2.5K service)
✓ Aftermarket housings indicate accident (check fitment, alignment)
Checklist References
- exterior#12: All lights function test
- exterior#76: Headlight condition (condensation, cracks)
- interior#84: Interior lights function
- exterior#82: Turn signal and hazard operation
Related Reading:
Next Steps
Professional electrical + light diagnostics → Complete function test, wiring checks
Check accident history → Insurance claims reveal headlight replacements
Lights fail gradually, then suddenly. Test everything before you trust anything.