1957 tail lights constantly on -

[Rocketdoc]

Lights were working fine. lights now all of a sudden both tail lights (not brake lights) on constantly. regardless of light or ignition switch both tail lights on constantly.
If I turn on indicator the opposite tail light goes out. Brake lights work fine independently. With ignition switch on tail lights still work continuously .Shop Manual not helpful.

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[cokefirst]

Something happened. If this is the tail lights only, then you have a short in the taillight wiring or a faulty light switch.

 

[Rocketdoc]

Something happened. If this is the tail lights only, then you have a short in the taillight wiring or a faulty light switch.

The other lights all work as designed with the switch. headlights and dash lights all light up with the switch

 

[cokefirst]

The taillights are fed by that switch. Do you have mice? If you did not have some service done just before this started happening, then you have a short in the system. it could be something as simple as the insulation rubbing through the taillight wires and inducing a current. Lights have to have power to turn on.

 

[55birdman]

Could it be brake lights on and not running lights?

 

[cokefirst]

If it is the brake lights and not the tail lights that are one, it is likely that the culprit is the brake light switch. The current switches, even those in familiar US manufacturer's boxes are made in China. I am sure they are quite capable of manufacturing a quality switch, but apparently they have chosen not to do so. I know of no quality brake light switch available in the US. That means you need to look for for an NOS switch that is US made OR, you can purchase a switch made by Hella. Unfortunately, they are not sold in the US even though Hella has a presence here. There is some kind of language barrier as I could not get an answer as to why the switches are not sold here and so I foun them in Austrailia. they are expensive but using their switch solves the problem.

 

[4VE]

Start by removing the connection to the dash switch. If they are still on, it is past that. Then try to find the inline fuse (there isn't a fuse block). If still on, the short is passed that. There are specialty manuals available for very affordable prices from Larry's. I got the Electrical manual and it is very handy.

 

[George Ford]

If it is the brake lights and not the tail lights that are one, it is likely that the culprit is the brake light switch. The current switches, even those in familiar US manufacturer's boxes are made in China. I am sure they are quite capable of manufacturing a quality switch, but apparently they have chosen not to do so. I know of no quality brake light switch available in the US. That means you need to look for for an NOS switch that is US made OR, you can purchase a switch made by Hella. Unfortunately, they are not sold in the US even though Hella has a presence here. There is some kind of language barrier as I could not get an answer as to why the switches are not sold here and so I foun them in Austrailia. they are expensive but using their switch solves the problem.

My brake lights seem to be very insensitive I have front discs w/o power so a hard pedal but I have to really press the pedal to light them up. could this be resolved w/ a new switch? I don't think they have allways been like this.

 

[Ward 57]

My brake lights seem to be very insensitive I have front discs w/o power so a hard pedal but I have to really press the pedal to light them up. could this be resolved w/ a new switch? I don't think they have allways been like this.

A new switch may be in order but I have not good things about the ones being made now. You might just pull the switch and make sure you don't have an air bubble in the foot of the switch limiting pressure on the switch diaphragm or air in the mounting block. Don't worry that you will loose any fluid as there is no pressure at rest and the system is closed so the vacuum will keep any fluid in the lines.

 

[paul5456]

The best bet to resolve the brake lights coming on only at high pressure is the mechanical switch sold by CASCO..

 

[Ward 57]

The best bet to resolve the brake lights coming on only at high pressure is the mechanical switch sold by CASCO..

At last resort. My hydraulic switch works perfectly but I replaced it 30yrs ago so still quality and working fine.

 

[CSPIDY]

Lights were working fine. lights now all of a sudden both tail lights (not brake lights) on constantly. regardless of light or ignition switch both tail lights on constantly.

Guys,
As you can read in Mr Rocketdoc’s first post
He clearly states it’s not the brake lights

As 4VE has recommended isolating the light switch is a great starting point