Car Electrical Problems NZ: Diagnosis & Repair Guide
Battery dying? Lights flickering? Our guide covers common car electrical problems, diagnosis tips, and what repairs cost in New Zealand.
Common Electrical Repair Costs
Battery replacement: $150-$350. Alternator replacement: $400-$800. Starter motor: $350-$700. Diagnostic scan: $80-$150. Electrical fault finding can be $100-$200/hour.
Common Car Electrical Problems
Dead or Weak Battery
Symptoms: Slow cranking, clicking when starting, dim lights, electronics not working
Common causes: Age (3-5 years typical life), leaving lights on, short trips, extreme temperatures, parasitic drain
Alternator Failure
Symptoms: Battery warning light, dimming lights at idle, battery keeps dying even when new
What happens: Alternator charges the battery while driving. When it fails, you run on battery only until it's flat.
Starter Motor Issues
Symptoms: Click but no crank, grinding noise when starting, intermittent starting
Quick test: If lights work fine but car won't crank, likely starter. If lights dim significantly, likely battery.
Lighting Problems
Symptoms: Bulbs blowing frequently, flickering lights, lights not working
Causes: Bad earth connection, voltage regulator issues, water ingress, loose wiring
Parasitic Drain
Symptoms: Battery flat after sitting for a few days, even with new battery
Common culprits: Aftermarket stereos, dash cams, faulty door switches, boot light staying on, alarm systems
Electrical Repair Costs
| Repair | Parts | Labour | Total |
|---|---|---|---|
| Battery replacement | $120 - $280 | $30 - $70 | $150 - $350 |
| Alternator replacement | $250 - $500 | $150 - $300 | $400 - $800 |
| Starter motor replacement | $200 - $400 | $150 - $300 | $350 - $700 |
| Fuse box repair | $50 - $200 | $100 - $200 | $150 - $400 |
| Window motor/regulator | $100 - $250 | $100 - $200 | $200 - $450 |
| Central locking repair | $50 - $150 | $80 - $150 | $130 - $300 |
| Wiring repair/trace | $20 - $100 | $100 - $300+ | $120 - $400+ |
DIY Diagnostics: What You Can Check
Safe to Check Yourself
- Battery terminals: Look for corrosion (white/green buildup). Clean with baking soda and water, then apply terminal protector.
- Fuses: Check the fuse box (under dash or bonnet). Pull fuses and look for broken wire inside. Replace with same amp rating.
- Connections: Ensure all battery connections are tight. Check earth strap from battery to body/engine.
- Battery voltage: Use a multimeter - should read 12.4-12.7V with engine off, 13.8-14.4V with engine running.
When to See an Auto Electrician
General Mechanic Can Handle
- • Battery replacement
- • Alternator replacement
- • Starter motor replacement
- • Basic fuse replacement
- • Bulb replacement
- • Simple wiring repairs
Need Auto Electrician
- • Intermittent electrical faults
- • Complex wiring issues
- • ECU/computer problems
- • Aftermarket installation
- • Alarm/immobiliser issues
- • Parasitic drain diagnosis
Battery Health Guide
Making Your Battery Last
- Typical lifespan: 3-5 years in NZ conditions
- Signs of aging: Slower cranking, needing jumps, age over 4 years
- Short trips kill batteries: The alternator needs 20+ minutes of driving to fully recharge after starting
- Heat is the enemy: Hot engine bays accelerate battery degradation
- Test before winter: Cold weather exposes weak batteries. Test in autumn.
Warning Lights Explained
| Light | Meaning | Action |
|---|---|---|
| Battery Light | Charging system fault | Check immediately - may be alternator |
| Check Engine | Engine management fault | Get diagnostic scan |
| ABS Light | Anti-lock brake fault | Normal brakes work, but get checked |
| Airbag Light | Airbag system fault | Airbags may not deploy - check soon |
| TPMS Light | Tyre pressure issue | Check pressures, may be sensor fault |
Preventing Electrical Problems
- ✓ Check battery terminals yearly - Clean any corrosion
- ✓ Use quality aftermarket installers - Poor installations cause faults
- ✓ Don't leave accessories plugged in - Even "off" they can drain
- ✓ Drive regularly - Cars sitting for weeks develop electrical issues
- ✓ Fix water leaks promptly - Water and electrics don't mix
Electrical Fault Diagnosis
Electrical faults can be time-consuming to diagnose. Unlike mechanical issues, a skilled auto electrician may spend hours tracing intermittent faults. Expect to pay $100-$200/hour for diagnostic time. A good technician will give you an estimate and keep you informed rather than just running up a bill.