Frequently Changing Headlights - 2004 Prius

First, are you buying high output bulbs as they are known to run hot and have short lives? Another possibility is that moisture has gotten into the housing and that can crack a hot bulb. A third possibility is that the inverter 12v charging circuit is putting out an excessive voltage (it should not be over 14v), but you can easily check that unlikely possibility.

I replaced the headlights once about two years ago as they were no longer at full brightness. No headlight failures to date on my 2004 Prius at 237k miles. I have had two tail lights burn out.

JeffD

 

Jeff have to disagree with you on that one.

While I agree excessive voltage will cause early failure the gen2 Prius is capable of charging at 14.6 volts if the battery is low and many cars that use the same bulbs with alternators run at 15 volts without problems.

Checking bulbs with a bench power supply and amp meter to run them on dip beam at 55 watts shows they are designed to run at 14 volts 3.9 amps, the main beam at 4.3 amps to give 60 watts although labeled nominally at 12 volts.

Again I agree the so called brighter bulbs burn out faster.

John (Britprius)

 

Brit,

If his Prius is charging at 14.6 volts, it is likely that the battery is toast anyways. I seldom see mine over 14v.

I was asking him to measure the charging voltage to eliminate the possibility that a failure mode was causing it to be excessive (15+).

JeffD

 

Jeff give this a try. Press the start button then get the Prius into the mode for reading battery voltage either by switching the lights on and off or by doing the finger dance, press the button again and turn on the headlamps for 5 minutes turn them off. Then put your foot on the brake and press start again, I guaranty you will see 14.4 volts on the MFD. If you load the battery further you will see 14.6 and this will gradually drop as the battery charges to 13.8 volts. This does not need to be a battery in a poor state of health.

John (Britprius)

 

If the bulbs you bought are made in China, they are of poor quality and burns out fast.
I have been changing out these Chinese made bulbs every 4-5 month on my wife's car as they are on all the time as DRL.

 

One longshot possibility could be that is not really true that your bulbs are dying but rather that you have a faulty socket.

This actually happened to me on my 2002 Audi A4. Only when I was called on to replace the second bulb in the same position within a few months did I take the trouble to check the "bad" bulb both visually and with an ohm-meter. It was just fine.

On that particular Audi model, the headlight bulbs sit in their own socket inside the larger headlight fixture. At a ridiculously high price that was still much less than replacing the entire cluster, I was able to replace the offending socket and have had no trouble since.

In this specific case I doubt this is what is going on as the original poster seems careful enough not to have been fooled the way I was, but possibly someone else who comes across this thread in trying to diagnose their own problem may be helped.