Headlights keep blowing out - No brights

[Frisbeeguy]

Well I'm back!

Darn it... I did the new harness, new lenses, new bulbs thing back in Jan. It seemed to be working fine, very bright and I could finally see at night for the first time ever in this car.

Not sure what bulbs I had in there - pretty high wattage halogens.

I noticed a burnt out bulb - drivers side.

Put in my replacement bulb that came w/ the wiring harness, it blew out.

Bought some new Silverstar's last night and when turning on the brights both brights blew and the passenger light also blew out.

Could the harness be bad?
It's wired directly into the solenoid that's on the drivers side fender-well.

Here's the thread I started when asking how to wire this up back then:
http://www.shoforum.com/showthread.php?t=114868

Thanks for helping... I'm off for the day and won't be back online until early Sun. morning so won't be responding / looking for the problem until tomorrow... going to play w/ my Frisbee's today!

 

[Frisbeeguy]

Any ideas anybody?
Can the harness be dad? I don't know what "relays" do - can they cause this?

Everything looks o.k. - Don't see any obvious shorts.

Could it be the turn signal multifunction lever ?

I really like the idea of not having all the headlights power not routed through the dash switch but maybe I should just put it back the way it was?

 

[Art5]

Are you sure those are not bulbs? Maybe you're touching them with dirty hands at the time of installation? Also when lights are on, touch the harness, where wires are out of insulation, if they are hot. What power output do your bulbs give out?

 

[SinisterSHO]

Is there water in your lights?

 

[Frisbeeguy]

Are you sure those are not bulbs? Maybe you're touching them with dirty hands at the time of installation? Also when lights are on, touch the harness, where wires are out of insulation, if they are hot. What power output do your bulbs give out?

I was real careful not to touch the bulbs during the installation.
The harness didn't feel unusually warm when I checked it after the last time the bulbs popped.

The first bulbs I think were about 100 - 80w?
The current bulbs are I believe 65 - 45w.
Not sure of the other set.

I've now talked myself into believing it's the multi-function switch since they both blew together when putting on the brights.

I'll replace that & then give it another try.

Thanks for the thoughts.

 

[hawkeye18]

You need to do a voltage check. Relays are just like switches; they either conduct voltage or they don't. They can't, by definition, modify it in any way (unless, of course, it's corroded, in which case it will reduce voltage, but that will cause the opposite of your symptoms).

There are generally only three reasons a light bulb will asplode suddenly: 1) voltage that's too high, 2) you touched the bulb with your greasy fingers), or 3) water in the housing shorting the bulb out.

2) and 3) are pretty easy to check and/or mitigate, but I think it's 1) that's causing your problems. Since your bulbs are relayed directly to the battery, if the alternator is overcharging your battery (>14.5v), that excess voltage will be supplied directly through the bulbs.

Since wattage is a function of current times voltage (P=I*E), and since most bulbs are rated at 55W, then at its rated voltage of 12v the bulbs are drawing about 4.6A (I=P/E). Since current draw remains constant regardless of supplied voltage, if you up the voltage to, say, 14.5v, you'll suddenly have a 68.7W bulb. That's almost a 25% increase in power, and since an incandescent bulb filament gets exponentially hotter with higher voltage, and heat is what melts the filament and causes it to burn out, I'd say it's a pretty logical source to your problem.

In any case, it's a simple matter to stick a multimeter on the charging system and see what the voltage is while the car's running. Putting the black probe on a body ground and the red probe on the positive terminal will get you an accurate reading. If it's anything above 14.5V, you need to look at getting a new alternator, or your current one rebuilt.

Are you having any other electrical problems?

 

[Frisbeeguy]

Is there water in your lights?

No - quite the opposite... it's been over 100 degrees everyday for a month and not rained this year!

The lights are new and everything worked well for several months. This just suddenly started happening.

I have been messing around w/ it though w/ a cam sensor problem that seems resolved. I'm sure it's not related.

Like I just stated above, I'll change the multi-function switch & then try it again w/ new bulbs.

 

[Art5]

I had one car that relay was doing some weired stuff, like I could turn lights off, but couldn't turn then on without turning on and off the whole circuit. And I had one relay flashing headlights all the time, no matter what. Check the fuse, it could melt sometimes in a way, that wires would touch together, and see if you have bulbs of less wattage than 100 to use on your harness.

 

[Frisbeeguy]

You need to do a voltage check. Relays are just like switches; they either conduct voltage or they don't. They can't, by definition, modify it in any way (unless, of course, it's corroded, in which case it will reduce voltage, but that will cause the opposite of your symptoms).

There are generally only three reasons a light bulb will asplode suddenly: 1) voltage that's too high, 2) you touched the bulb with your greasy fingers), or 3) water in the housing shorting the bulb out.

2) and 3) are pretty easy to check and/or mitigate, but I think it's 1) that's causing your problems. Since your bulbs are relayed directly to the battery, if the alternator is overcharging your battery (>14.5v), that excess voltage will be supplied directly through the bulbs.

Since wattage is a function of current times voltage (P=I*E), and since most bulbs are rated at 55W, then at its rated voltage of 12v the bulbs are drawing about 4.6A (I=P/E). Since current draw remains constant regardless of supplied voltage, if you up the voltage to, say, 14.5v, you'll suddenly have a 68.7W bulb. That's almost a 25% increase in power, and since an incandescent bulb filament gets exponentially hotter with higher voltage, and heat is what melts the filament and causes it to burn out, I'd say it's a pretty logical source to your problem.

In any case, it's a simple matter to stick a multimeter on the charging system and see what the voltage is while the car's running. Putting the black probe on a body ground and the red probe on the positive terminal will get you an accurate reading. If it's anything above 14.5V, you need to look at getting a new alternator, or your current one rebuilt.

Are you having any other electrical problems?

Whoa, that's a mouthful!
Thanks for the well thought out analysis and possible solutions.
Bulb housings are definitely dry and new bulbs installed from package to retainer untouched.
No other elect. probs. at this time.
Popped in a new bulb today and it works fine... I didn't attempt to flash my brights.

When new switch arrives - will pop it in and hope for the best!
Now I really need to study the "paint" threads. My car looks like crap.

I will check the voltage output as well. Had the alternator rebuilt some time ago.

 

[Frisbeeguy]

I had one car that relay was doing some weired stuff, like I could turn lights off, but couldn't turn then on without turning on and off the whole circuit. And I had one relay flashing headlights all the time, no matter what. Check the fuse, it could melt sometimes in a way, that wires would touch together, and see if you have bulbs of less wattage than 100 to use on your harness.

Ya, that's some crazy stuff when things melt down.
The fuses are ok - just blowing bulbs when switching on the brights.

Will post again after new switch installed.

 

[Frisbeeguy]

Time to resurrect this thread...
After installing a new (used, bought from another forum member... bought two - first one was wrong one) multi-function switch all work O.K. for awhile.
Once again - bulbs are blowing as soon as I try to use the brights.
Installed two new bulbs on the way to get inspected and both brights blew immediately upon being switched on.

Did I install the wiring harness incorrectly?
Could the harness be pushing too much power through the MFS?

I really need to see around here at night & the stock set-up didn't cut it but this is not an improvement!

Any ideas?