Thought I'd ask before..

[Willtyat]

trying to chase this down. This is weird, my left tail light stays on all the time, including when then ignition is off, except when I turn the right turn signal on. So when I shut the truck off I have to turn the right signal on or I'll come back to a dead battery. Any ideas?

Thanks Bill A.

[fordman]

that sounds like a bad turn signal switch. if it was both tail lights i might say brake light switch not closing.

[70_F100]

that sounds like a bad turn signal switch. if it was both tail lights i might say brake light switch not closing.

[Willtyat]

Cool, Thanks. Then that's where I'll start

[tsherry]

I had that on a manual transmission Falcon. The clutch/brake pedal bushings were shot, allowing the pedals to shift out of place significantly when the clutch was pushed in. As it got worse, the stoplight switch grounded out one leg of the wires, allowing the LR taillight to stay on and kill the battery.

It was not fun to fix, but once the pedal support was replaced, life was good.

[70_F100]

I had that on a manual transmission Falcon. The clutch/brake pedal bushings were shot, allowing the pedals to shift out of place significantly when the clutch was pushed in. As it got worse, the stoplight switch grounded out one leg of the wires, allowing the LR taillight to stay on and kill the battery.

It was not fun to fix, but once the pedal support was replaced, life was good.

I'm really not sure how that was possible (only one light staying on) just because of the bushings.

There are only two wires going to the brake light switch (one power, the other to the lights), so if the brake light switch was staying activated, both rear lights would stay on.

[Thunderfoot]

Sounds like you might have more then one problem to me...
There is no power to the TSS with the key off other then from the Brake lights if the brake switch is activated, so the brake light switch would have to be stuck on... so a bad TSS will not do this particular symptom...

Do both your brake lights work when you hit the brakes?
Do your turn signals work as they should?
Are you sure it is the "tail light" that is on and not the "brake light"?

If it is the tail light then you have some messed up wiring somewhere, either in the back of the truck where someone wired in a trailer plug or could also be under the dash going to the TSS or short somewhere else... I'm leaning more towards a mis-wired trailer plug...

Also, double check the bulb in the tail light and be sure it is an 1157 bulb, however once again there should be no power hear with the key off with the exception of the brake light switch being stuck on or being depressed. But wrong bulb, a bad TSS and a stuck on brake light switch all combined could do something like this...

My

I had that on a manual transmission Falcon. The clutch/brake pedal bushings were shot, allowing the pedals to shift out of place significantly when the clutch was pushed in. As it got worse, the stoplight switch grounded out one leg of the wires, allowing the LR taillight to stay on and kill the battery.

It was not fun to fix, but once the pedal support was replaced, life was good.

On these trucks there is only one power wire from the brake pedal to the TSS, it is the TSS that splits it out to both rear bulbs and also turns one or the other off when making a turn. The power for this comes from the brake light switch and then goes to the TSS and then to the rear of the truck, so a bad TSS alone would not do this particular symptom.