2011 Prius blows headlamps way too often, not HID

i agree, nevertheless, TSB for defective wiring resulting in bulb failure is a fact. BTW, the circuit is more than 12V, its as high as mid 14'sV and maybe even more when just switched on (transients). Maybe the "improved" wiring has more inductance or resistance?

exactly!

 

My 2010 has blown 6 or 7 in 94K miles, I assumed it was bad design and higher than usual vibration that was doing it (I use it a lot for deliveries, going off and on the road to mailboxes).

 

Do you also leave the headlight switch in the On position when shutting down/starting car?

 

Yes, the transients when converter is turning on/off could be the reason. But more likely to me is low voltage on bulb. Anybody ever measured voltage on running bulb ?

- Alex

 

According to earlier posts that detailed the problem, the "improved" wiring has lower resistance.

 

OK, how that prevents the frequent burnouts issue?

 

Upon reading few posts and the Toyo parts kit, it consists on installing a heavier wire gauge to such headlamps assembly.
For the vehicle owners out of warranty (36k miles) it's a 3 shop labour hours by Toyo standards .

 

Lower resistance = higher current, hotter filament. In turn, that equals to higher brightness. Hotter ( but within specification, unlike too low temperature with faulty wiring) allows halogen cycle to restore the filament by returning evaporated material back to the filament. That should provide the extended life of the bulb. Should be around 1000 hours for standard bulbs, and close to 400 hours for "+30%" or alike bulbs.
Alex

 

if the defective wiring lowered the filament temp that much, the lights would be visibly dim and yellow. not sure I buy it, but at least it's a possible explanation.

 

In other words, according to the official theory about the halogen cycle, slightly lower than intended voltage reduces life of these bulbs, while with even lower voltage they would be "visibly dim and yellow" but last a long time, typical of ordinary incandescents operated at substantially sub-normal voltage.