Blowing Rear Taillight signal bulbs

[bandt]

Hey Guys,

Seem to be having trouble keeping tailight bulbs in stock. Drivers side blew first, now the pass side. Replaced pass side and after 10 min of driving it went again. Once blown signal stops flashing. Have done some wiring in the car, maybe I did something. What would cause bulbs to go?

Any suggestions? 

[ShelbyDogg]

Check your voltage at the battery, then at the tail light socket. High voltage will blow bulbs. I once blew out all of my lights, running my car without the battery in the car. 15 bulbs had to be changed out. The only ones working to get me home were the high beams and brake lights. No battery load brought the voltage way up.

Anything else blowing beside the tail lights?
 

[bandt]

Just seems to be the signal bulbs that are blowing. I am using a battery tender and ran a dedicated power lead from the alternator to the starter relay to bypass the ammeter. Not sure if that could cause excessive voltage though.


Brian

[the_engineers]

Bad voltage regulator?

[ShelbyDogg]

Bad voltage regulator?

You really need to put a voltmeter to the socket and see what kind of voltage you're getting to the bulbs. if it never gets higher than 15v, then you are just getting a bunch of bad bulbs and you should try a different brand.

[bandt]

I'll check voltage at the socket, thanks.

[mrwfp]

I had a similar problem with my '73 'Cuda years ago except the fuse keep blowing, not the light bulbs.  As it turned out the cigarette lighter and the tail lights were on the same fuse and the lighter had a short that blew the fuse.  Have you checked the fuse to see if it is the correct size?  If the fuse is sized incorrectly and you have a short like I did, the bulbs will probably burn out way before the fuse.  It's just something else to consider and look at when everything else leads nowhere.

[bandt]

Can someone describe what happens typically when a signal bulb goes?
This seems weird.
The situation with the bulb that will no longer flash, the rear parking light works normally with the other filament and with the signal on the second filament will come on solid like the brake light is on but the flasher won't come on. So the bulb seems fine but it won't engage the mechanical flasher under the dash. This has happened with both sides. If I replace the bulb it will work normally for a while then same thing happens. The bulbs appear to be fine they just won't turn the flasher on???

[bandt]

Checked with a voltmeter I have 14.50v with the engine off and battery in storage mode on tender.  I wonder what the voltage is at high RPM, maybe it does go over 15?

[ShelbyDogg]

Can someone describe what happens typically when a signal bulb goes?
This seems weird.
The situation with the bulb that will no longer flash, the rear parking light works normally with the other filament and with the signal on the second filament will come on solid like the brake light is on but the flasher won't come on. So the bulb seems fine but it won't engage the mechanical flasher under the dash. This has happened with both sides. If I replace the bulb it will work normally for a while then same thing happens. The bulbs appear to be fine they just won't turn the flasher on???

Your bulbs are good and you have a bad ground at the socket.  I actually take a black wire and solder it to every tailight socket including my 2 side marker lights then ground it to a screw. You will never have tailight ground problems again.

You can verify this by holding a ground wire to the socket while watching the bulb.

[bandt]

Now I'm really confused.

New bulbs, tried grounding the housing right to the battery, checked to see if I have power from both signals to the flasher at the column (I do), parking lights work, when signal is put on it goes on steady (won't flash), hazardz work, unplugged cig. lighter (no difference)

[barracuda7199]

what about trying a new flasher? there cheap worth a shot.

[ShelbyDogg]

what about trying a new flasher? there cheap worth a shot.

Yes try the flasher. I usually just grab the emegency flasher and switch it with the turn signal flasher to rule it out. Same flasher works both left and right sides. The emergency flasher is a higher load flasher, should blink the side faster, but should work.

I guess I was puzzled because you said the bulbs "blew" and new ones fixed the problem for a little while, but then said the bad bulbs were still good.  You should have tried the flasher first, when the sides came on solid and didn't blink.

[bandt]

I'll try a flasher see what happens.
Originally replacing the bulb would cure the problem, seems there's more to it now.

[bandt]

Update,

After all that a $4.00 flasher did the trick. Thanks guys.