Stop light and tail light problem

[Johns30]

New member here. I have a 1930 town sedan (Murray) that I acquired about 2 months ago. Very nicely restored about 8 years ago, but not perfect. Will try to get some pictures for the Barn soon. This site is awesome!

I've done a lot of reading and searching of other threads on the subject but still can't seem to figure my stop light problem out yet. I'm a total newbie to Model A's and am not good with electrical gremlins .
I "think" everything worked when I bought it but not 100% sure. I've added a disconnect switch from Snyders on the ground side recently which works awesome -I have a hard time believing that has anything to do with this problem but that's the only thing I've messed with so far. Car is original 6V positive ground.
Here are the facts:
1. Electrically, everything on the car works as it should except for this problem.
2. When I depress the brake pedal with nothing else on, neither brake light works.
3. If I turn on the cowl lights or headlights, both tail lights DO work.
4. With the cowl lights or headlights ON, if I then depress the brake pedal, the driver side brake light comes on, but the passenger side does not (and further, the passenger side tail light then goes off). All bulbs are ok since I've tried them on both sides, and have also tried new ones.

I believe my brake light switch works properly due to #4 and since I've tried bypassing it with no difference. I have a test light and have verified that there is no power coming into the brake light switch UNLESS the cowl or headlights are on. Weird.

Lastly, I bypassed the "bail" with a lead directly from the starter to the brake switch, and still there's no power coming into the brake light switch (this was something Tom Endy suggested in another post to see if it is a problem inside the "bail").

Sorry for the length of this post. Could this be a ground problem, maybe in the passenger brake light side? If so, how would I test this or fix this? I know everyone says bad grounds can cause weird problems but I don't know how to go about finding a bad ground. I would need someone to dumb it down for me...a lot . Or any other ideas as to how to trouble shoot this?
Thank you in advance!

[Bob C]

Usually when you have a condition of a light that is on going out when another
one comes on it is because of a grounding problem. I would try running a known good ground to the taillights and see what happens.

Bob

[Bruce Adams]

Does the amp meter move when you apply the brakes?

Did I read you "bypassed it with no difference"? If by that you mean you ran a hot wire to the brake Light and it did not light, its your ground or bulb. Check the bulb with an ohm meter.

[Tom Wesenberg]

I can't imagine you still have no power at the brake switch if you run a new wire from the starter switch to the brake light switch. Your new wire would have to have a break inside the insulation or someone crimped on the terminals and didn't strip the insulation off the end of the wire that gets crimped. I saw this happen on a brand new Ford that had an intermittent ignition problem. The car would start and run when I got to it, but later it would die going down the road. Finally I spotted the coil primary terminal with insulation still on the end of the wire.

[Mike V. Florida]

Here are the facts:
1. Electrically, everything on the car works as it should except for this problem.
2. When I depress the brake pedal with nothing else on, neither brake light works.
3. If I turn on the cowl lights or headlights, both tail lights DO work.
4. With the cowl lights or headlights ON, if I then depress the brake pedal, the driver side brake light comes on, but the passenger side does not (and further, the passenger side tail light then goes off). All bulbs are ok since I've tried them on both sides, and have also tried new ones.

First and foremost welcome!

Do you have this wiring diagram?

If you look at the drawing you will see the one part that is common to all the lights. The light bail on the bottom of the steering column in the engine compartment. Did you knock it loose?

[Brentwood Bob]

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I had to replace a new wiring harness a year or so ago due to same type of problem. This could be one of the bad harnesses.
Bob

[Patrick L.]

The taillights are completely separate/independent from the stop lights.

Between Mikes wiring diagram and a plain ole test light this can be fixed.

Its not hard to run some of your wires if need be.

Use the test light to look for power where it needs to be and can help find a poor ground. Separate/extra ground wires can be added and fairly well hidden.

It appears to me that you have both issues, poor ground[s] and improper wiring.

[emf]

I had a similar problem on a different old car and it was tough... I finally replaced all of my two filament bulbs and the problem disappeared. One of the bulbs had one filament touching the other and caused the problem. The rest of the bulbs were OK, but changing all of them helped me get closer to the problem. Investigate the filaments, your lights may have been altered....

Frank

[Tom Wesenberg]

Good point Frank, as some years back I also had one filament break, then move over and touch the other filament. That will make you scratch your head for a while.

[Johns30]

Thank you for all of the ideas. I will try to get back and keep working on this in the next few days or this weekend. If I have success, or still stumped, I will report back!

[Johns30]

UPDATE: Oh man, I think I'm dealing with two problems at the same time, but I may be getting to the bottom of it. I think "Patrick L" hit the nail on the head with his response above about having two issues at the same time .

I've apparently got a bad ground by the passenger side tail/stop light fixture. A wire lead with alligator clips between the fixture housing and a bolt on the luggage rack allows the brake lights to work properly (assume that adds a proper working ground), BUT the brake lights still only work if the headlights or cowl lights are turned on.

So, I then went back and again bypassed the "bail" by adding a direct lead between the starter switch and the brake light switch.

With the "bail" bypassed, AND with the extra ground on the light fixture, both brake lights work properly when the brake pedal is depressed.

So I think I need to fix two things. The bad ground at the rear passenger light fixture, AND I probably need to investigate/take apart the "bail" to see if something in there is loose or crossed?

Does this sound like a plan? As a newbie, I am nervous of messing with that bail, so I'll have to do some research on threads here first before I attempt to take that off/apart.

How would I go about fixing the fixture ground problem? (without adding a permanent/additional ground wire if possible). Is it just a matter of seeing if the bulb housings are rusty, or ??

Thanks so much for the help!

[Tom Wesenberg]

You just need to move the jumper wire around to see where the ground is lost. Sometimes it's the light socket to the light housing. Or it might be the housing to the arm, or the mounting arm to the fender.

Yes, you are right to take the light switch housing cover off to find out why the brakes don't have full time power.

[CT Jack]

Bite the bullet and run ground wires from the frame or fender bolts to each light socket base. Using an ohmeter/continuity tester verify each ground is grounded. Remember the tail light is mounted to a bracket that has a rubber gasket between it and the fender. You should not assume the mounting bolts are in contact with the fender (ground). Once you have made certain all light bases are grounded then you only have to deal with one (-) 6volt wire.
The aftermarket rotary light switches are all pieces of junk to put it bluntly. I have had many problems with mine to the point where I have bypassed some of the connections by redirecting them to a toggle switch hidden under the dash. This arrangement works flawlessly.
You should also run a heavy gauge wire from the battery ground cable to an engine bolt. The engine theorectically could be electrically isolated from the frame as it is mounted on three nonconductive rubber pads. Doing this eliminates potential poor grounding related problems that could drive you crazy trying to resolve.

[Patrick L.]

Originally Posted by Johns30

UPDATE: Oh man, I think I'm dealing with two problems at the same time, but I may be getting to the bottom of it. I think "Patrick L" hit the nail on the head with his response above about having two issues at the same time .

I've apparently got a bad ground by the passenger side tail/stop light fixture. A wire lead with alligator clips between the fixture housing and a bolt on the luggage rack allows the brake lights to work properly (assume that adds a proper working ground), BUT the brake lights still only work if the headlights or cowl lights are turned on.

So, I then went back and again bypassed the "bail" by adding a direct lead between the starter switch and the brake light switch.

With the "bail" bypassed, AND with the extra ground on the light fixture, both brake lights work properly when the brake pedal is depressed.

So I think I need to fix two things. The bad ground at the rear passenger light fixture, AND I probably need to investigate/take apart the "bail" to see if something in there is loose or crossed?

Does this sound like a plan? As a newbie, I am nervous of messing with that bail, so I'll have to do some research on threads here first before I attempt to take that off/apart.

How would I go about fixing the fixture ground problem? (without adding a permanent/additional ground wire if possible). Is it just a matter of seeing if the bulb housings are rusty, or ??

Thanks so much for the help!

I don't think it makes much difference where power to the brake switch comes from, but, its suppose to come from the power/batt lugs of the light switch. Its the same portion of the switch that is fed by the wire from the cut-out and horn.

Bad grounds can be a PITA at times. They can also be as simple as a 'jiggle' of a mounting bolt/screw. I don't have a problem with soldering a wire to a light socket and running it to a good spot on the frame if need be. But, soldering can be tricky if you're not used to it. Sand, sand,sand, clean, clean, clean and flux.

[Brentwood Bob]

On the misswired replacement harness i had to change out (#6) The switch plate did not make cood contact with the rotary switch. If the harness appears to have been in service for years Look for frayed insulation, leads making cross contact, or a dirty, greasy mess.
Please report back. Bob

[lcslaw]

CT Jack, I am about to replace a wiring harness on my 30 Tudor which was restored about 15 years ago for the 3rd time in last 3 years. It seems the contacts don't stay tight for bright and dim headlights while coach lamps and tail and brake lights seem ok. I am ready to bypass the bail and wire directly to a toggle switch for high and low beam under the dash and would appreciate some detailed guidance. I think I have an idea on the how but really don't want to screw it up. Thanks for any guidance.

[Tom Wesenberg]

Other than using a few extra feet of wire, I never understood why so many old cars used a complicated through the steering column light switch, rather than a simple toggle or rocker switch for the lights.

[SeaSlugs]

Originally Posted by Tom Wesenberg

Other than using a few extra feet of wire, I never understood why so many old cars used a complicated through the steering column light switch, rather than a simple toggle or rocker switch for the lights.

im not sure either... was it to save wire? was wire rather expensive back then?(copper)

I mean where its at it is a convenient place for wiring goes...

EDIT:

if you google image search the BIG cars back then (packard, cadilac, lincolns), during model T era they all had dash mounted headlight switches. then in 27/28 they went to steering wheel controlled headlight switches. Was it a way for the model A to feel more sophisticated to the driver? Think about things like features or styling of high end cars today, and like back then, everybody copys them so the guy in the economy box can feel like he owns a Mercedes. Notive how many cars now have those white LED DRL lights under the headlights now? Audi started that trend about 5-7 years ago...

[Ed Saniewski]

Icslaw, are you having a problem with the high/ low light connection at the headlight? Or is it when you move the light control at the steering wheel?

[katy]

Other than using a few extra feet of wire, I never understood why so many old cars used a complicated through the steering column light switch, rather than a simple toggle or rocker switch for the lights.

That's like I don't understand all the newer cars w/their complicated "multi-function" stalks on the steering column, rather than individual switches.
I was told it's "European" styling, big deal, I prefer the older "North American" styling, less complicated, even a dummy like me can find which switch to turn on.