tail light stays on

robw

robw

Senior Member
My tail light stays on constantly... does not matter what position the switch is in.

Before I start chasing wires and trouble shooting switches... is there anything specific I should look for?

All the other lights turn on and off normally.

Rob
 
I agree with Hicktick, that it's usually a stuck or bad brake light switch that keeps the brake lights on. If it's truely the tail light staying on, it could be a wire strand touching the power lead in the headlight switch.
 
Brake light works properly. The problem was discovered when I replaced the burned out tail light.

Head lights have two lights... it is an early '29.

Rob
 
My money is also on the switch. A Model A mechanic that works on my cars told me the first thing you check when the tail lights stay on is the brake light switch. Twice the cure has been a new switch ( they are cheap ) !
Al
 
I'm wondering if this car might have the "4-finger" light switch as described by Tom W. in a different post. Meanwhile, the lighting harness (when was this replaced if ever) might be of the "3-finger" type.

Most don't know that the twolight and fluted lens setup/harness/switch was electrically radically different. Today the parts gurus only sell the twolight harness: when mated with the 4 finger switch this can cause problems like this.

If you have the 4 finger switch then you're in my envy as I'm attempting to resurrect my March 29 truck back to fluted lights. Right now I can only aim for a twolight switch with a re-wire and "don't turn to the 4th position solution" (which isn't bad - it works - but its not what it was.)

Joe K
 
the brake /stop light switch works the brake lights period two , completely separate circuit from the tail lights. rob says the brake lights are fine but the tail lights stay on. i also would look at the light switch (spider).
 
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My 29 does the same thing, I feel as Mitch says it's in the spider, if I wiggle the lever I can get to go off. I shut the battery off every time as a matter of habit now which I think is a good idea with these cars anyway.
 
Found the problem... the tail light wire was plugged into the wrong contact on the switch.
 
which tail light is the correct one? Mine is supposed to be a double contact bulb. Mac's catalog has a single contact bulb, and Snyder's assumes you know what part number you are looking for. I have an extra double contact bulb, but it is too big to fit under the cover.

rob
 
robw said:
which tail light is the correct one? Mine is supposed to be a double contact bulb. Mac's catalog has a single contact bulb, and Snyder's assumes you know what part number you are looking for. I have an extra double contact bulb, but it is too big to fit under the cover.

rob
Click to expand...

Not sure about the double contact bulb. IIRC either the drum or teacup light uses two single contact bulbs.

You say early 1929? If that the case then your truck (assuming it's red) may have either a drum or a teacup. My march 29 truck was originally drum. Now converted (for expediency) to teacup. Shortly to go back to drum.

Ford used up a lot of car production outmoded parts by sending them out on the commercial vehicles. My gearshift was painted black - I assume it was defective plating (its plated underneath) and so considered unsuitable for the car lines.

My truck had fluted lens headlights along with the drum taillight. Probably also originally had a powerhouse generator - although the engine had been replaced and along with it likely the generator to long version.

I've discussed my issue with the "four contact vs three contact" headlight switch.

Some of the later teacups (30s production?) may have used a double filament bulb. Dunno on this.

Joe K
 
I've got the three button switch, and a drum tail light.

DSCN6161_zps56c04a9b.jpg


DSCN6158_zps84c77840.jpg


I've also got fluted lenses on the headlights, but two lights in each...

Rob
 
Not sure about the double contact bulb. IIRC either the drum or teacup light uses two single contact bulbs.
Click to expand...
I said that earlier and perhaps I should have said "two single filament bulbs." I see the your license plate bulb is two contact. Assuming that original. (It's been at least three years since I've looked at my truck and the drum taillight replacement from A&L is still in it's box.)

Your truck SHOULD have had the four finger switch since it has fluted headlights. This may have been changed? Turn switch to 7:00 position and you get parking lights, center is off, and 5:00 is head lights only? With the 3 finger switch you get four positions. 7:00 is parking, center is off, 5:00 is Low Beam 4:00 is high beam.

I think I'm going to let Tom W. jump in here and confirm a thought for me. I think someone replaced your headlight switch with the later switch and changed/adapted the wiring to do a single filament headlight bulb. I don't think you can change the headlight sockets to make a fluted headlight into a twolight headlight though. Tom will know.

Tom also has the pix (and the references to previous discussion) which show the differences between the headlight switches.

I'll admit though, this is FUN because your truck is so similar to my truck, both in dating and wiring. But I operate under such a handicap that my truck is neither original (although I'm trying to make it so) nor in front of me (I'm traveling on business until the end of the month.)

Joe K
 
Hmmm..

borrowing from Tom W's posting in another thread...
Tom Wesenberg said:
HeadlightSwitch.jpg


Flutedswitch-1.jpg


Here you can see how the switches and contact plates differ from the fluted headlights and the Twolite lamps, with the top picture being the later style Twolite system. The top right cover is the longer cover used in 1930-1. You can see two styles of contact plates used with the Twolite switches, with the one of the right with 9 brass contacts being the more common one by far.

BTW, for those wondering how the Caswell copy cad plating system looks, these are parts I plated using my Caswell kit.
Click to expand...

My switch looks like the upper middle one.

My headlights have two lamps in them, but only seem to have parking, off, headlights.. and that is it. no choice between high and low beams.

who knows.. I may have some weird combination.
 
robw said:
Hmmm..

borrowing from Tom W's posting in another thread...


My switch looks like the upper middle one.

My headlights have two lamps in them, but only seem to have parking, off, headlights.. and that is it. no choice between high and low beams.

who knows.. I may have some weird combination.
Click to expand...

My truck came with headlamp shells - and twolight reflectors, lenses, rims (which can fit either) The former owner had a 30 roadster and he was obviously dressing this up for the sale. No headlamp sockets although there was a hand switch drilled and installed on the dash rail (GRR!) Not even a switch rod in the center of the steering column. Non-functional.

Buying parts enough to install headlights I quickly found that the shells I had were not Twolight. So I bought the necessary aftermarket sockets, installed the twolight bulbs, and came up with a three finger twolight switch out of a basket-case 30 ford, and ran the wires through the conduits without landing plugs on the bottom of the headlights. It looked OK to the passerby and it all went together into a functional unit. My harness like yours was an aftermarket with 9 rivets.

Now, I've pretty much determined the truck was originally fluted headlights with a drum taillight - elsewhere on another thread I describe finding the drum tail-light bracket in the pocket behind the drivers shoulder - my only clue of what the truck likely had originally.

You don't say if your light switch body is aftermarket. A lot of these are at best 'flaky.' Work/don't work/short out/open circuit. But since you obviously have a twolight harness, someone must have modified the harness. And what you see parking-off-headlights (no lo-hi beam), is in the fluted headlight pattern.

I wish I had your solution to the tail light. T-light should be on with either parking or headlight - but certainly not on while switch is OFF. Best I can suggest is to start at the tail-light and follow that wire back to the switch-plate, and then see if and when the three dimples hit it to make it work. You should be able to "simulate" the function of the switch by doing a three point jump (or making a triangle shaped jumper out of a piece of sheet aluminum.)

Hmm. I wish I were there. I know exactly what I would do next based on my description above. Alas. So near and yet so far.

Good luck.

Joe K
 
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