Running lamps fuse blowing

[fine69]

Hi all. I was just about to set off for an evening cruise last night and decided to do a quick light check and good thing I did. Headlights were on but tail and park lamps were not. Brake and signal lights all worked too. I checked my fuse box and sure enough the 20amp tail lamp fuse was cooked. I changed it and hit the light switch and it just burned out immediately. I’m no electrical wiz but checked the battery side of fuse block and saw about 25V, load side was not showing anything for resistance (not sure if I’m reading the meter correctly). Where should I be looking here and what should I be looking for? I know my lights were working perfectly fine just a few days ago and this all of a sudden happened.
Oh and can someone tell me what the correct current amount is for my far right fuse (instrument )? It’s worn off and I can’t make it out.
Thanks

 

[1967coronet]

A few things to check.
Pull the bulbs front and rear see if you have power to each socket and if the fues is holding.
I think there is a connection behind the left kick panel for the rear wiring.
Sometimes left side sill plate screws get into wires not stored in the channel,
Pull the rear seat bottom check wires that continue along the left side and over wheel arch.
Also years ago many of these cars had a hitch installed at one time , look under the rear bumper area for old wiring and crimp connections.
License lamp is on the same circuit also.

 

[Sinitro]

Hi all. I was just about to set off for an evening cruise last night and decided to do a quick light check and good thing I did. Headlights were on but tail and park lamps were not. Brake and signal lights all worked too. I checked my fuse box and sure enough the 20amp tail lamp fuse was cooked. I changed it and hit the light switch and it just burned out immediately. I’m no electrical wiz but checked the battery side of fuse block and saw about 25V, load side was not showing anything for resistance (not sure if I’m reading the meter correctly). Where should I be looking here and what should I be looking for? I know my lights were working perfectly fine just a few days ago and this all of a sudden happened.
Oh and can someone tell me what the correct current amount is for my far right fuse (instrument )? It’s worn off and I can’t make it out.
Thanks

View attachment 1723548

No idea where the 25V came from..
Tailight fuse should be either a 10A or 15A... 1st check for a shorted bulb/socket, or U may have a shorted, frayed wire where it passes through a grommet in the trunk...

Just my $0.02....

 

[fine69]

No idea where the 25V came from..
Tailight fuse should be either a 10A or 15A... 1st check for a shorted bulb/socket, or U may have a shorted, frayed wire where it passes through a grommet in the trunk...

Just my $0.02....

25V showed up on the multi-meter. And maybe my eyes deceive me but is that not “20A” above the slot for “TAIL LMPS” in my photo (the one with the missing fuse)?

 

[Black_Sheep]

A few things to check.
Pull the bulbs front and rear see if you have power to each socket and if the fues is holding.
I think there is a connection behind the left kick panel for the rear wiring.
Sometimes left side sill plate screws get into wires not stored in the channel,
Pull the rear seat bottom check wires that continue along the left side and over wheel arch.
Also years ago many of these cars had a hitch installed at one time , look under the rear bumper area for old wiring and crimp connections.
License lamp is on the same circuit also.

Yes there should be a connection behind the kick panel. I would unplug it to isolate the front and rear lights. If the fuse still blows the problem is in the front lighting wiring. If the fuse does not blow the problem is in the rear light wiring.

 

[twecomm]

Before getting into chasing wiring issues, you might want to try removing all lamps involved, tail lamps and front parking lamps, license plate lamp, and see if the fuse still blows with NO load applied. If still taking out the fuse, then it's wiring related.
It's possible to have an internal short in a individual lamp from a broken filament creating an internal short. While lamps are out, you can visually inspect them and even test each one of them if you want.

 

[fine69]

Before getting into chasing wiring issues, you might want to try removing all lamps involved, tail lamps and front parking lamps, license plate lamp, and see if the fuse still blows with NO load applied. If still taking out the fuse, then it's wiring related.
It's possible to have an internal short in a individual lamp from a broken filament creating an internal short. While lamps are out, you can visually inspect them and even test each one of them if you want.

I like that idea. If the issue were to be tail lights then it would have to be one of the “inner” bulbs, correct? Seeing as the brake lights still work

 

[twecomm]

The bulbs have dual filaments, one filament for normal illumination and a second that adds in for the brighter stage of illumination for brakes and turn signals. I would visually inspect that the bulbs don't have any loose junk inside that could create a short. Also inspect the sockets while you have the bulbs out. Since the terminal pad in the socket is spring loaded ,it's possible that there could be a loose wire or something in a socket with bulb installed vs. with bulb removed.

 

[fine69]

The bulbs have dual filaments, one filament for normal illumination and a second that adds in for the brighter stage of illumination for brakes and turn signals. I would visually inspect that the bulbs don't have any loose junk inside that could create a short. Also inspect the sockets while you have the bulbs out. Since the terminal pad in the socket is spring loaded ,it's possible that there could be a loose wire or something in a socket with bulb installed vs. with bulb removed.

I located the connection in the kick panel and undid it. The fuse did not blow when reconnecting the battery. Then i reconnected the plug in the kickpanel, pulled all the tail lamp bulbs and reconnected the battery - no blown fuse. Other than being dusty, none of the sockets looked too terrible. However I am a bit suspicious of one of the 1095 bulbs. I’ll try find some tomorrow at a parts store. I’m down to my last 20A fuse too haha.

 

[twecomm]

Sounds like you have narrowed it down to socket of bulbs. Please do report on what fixes your problem, we all like to know..

 

[fine69]

Sounds like you have narrowed it down to socket of bulbs. Please do report on what fixes your problem, we all like to know..

Well I struck out on the 1095 bulbs today. Came home with #89s instead. At first I plugged them in and one was on, the other wasn’t. I checked with a test light and it lit up but the bulb did not, even when touch the light housing. I switched bulbs around to see if one was a dud but it must have been a dirty contact because I plugged them both back into the housing once more and then they both lit up! So I’m not 100% sure what was causing the original short but it must have been one of the old 1095 bulbs?
Here’s what the tail lights look like with 89s instead of 1095s: