Directionals switch
 

1950 Ford Custom - We are having an issue with the directional signals or switch.

At one point they were working, but are not working now. So, assume the switch is wired correctly. All the other lights function correctly - parking lights (front and rear), and brake lights. Just using the direectionals with all other lights off seems to do nothing, but what is happening, when we depress the brakes and activate the switch to turn on a directional, the brake light on that side that was activated shuts off. I think that is correct as I thought the brake light would cut off and the regular tail light would then flash. I have checked and we are getting voltage to the flasher unit (it is a two prong flasher unit). We replaced the flasher unit with the same part, and still nothing.

My guess would be it is the switch unit itself. Does that make sense? And if so how difficult is it to get into the back of the turn signal switch to check the wiring and mechanicals of it? Switch model number: KD-728 - not sure if that was issued by Ford or if it is aftermarket, but it's pretty old.

Thanks.

Re: Directionals switch
 

Actually it's the brake light element that needs to flash. I believe you need to recheck your wiring as it is wrong. The KD-728 is an aftermarket switch and you can probably find a wire diagram on-line for that switch.

Re: Directionals switch
 

If the wiring is wrong, how is it that it worked last year. Nothing has changed. So, if the brake light is supposed to flash - it currently is just turning off, and never comes back on. The front parking lights used to flash before, and now ... no.

Re: Directionals switch
 

I suspect you have a bad ground somewhere, or a bad fuse.

Re: Directionals switch
 

2X bad ground

Re: Directionals switch
 

Would that make sense even though all the lights function otherwise if the directional switch is not activated? Could it be that something in the switch itself is shorting to ground when activated?

Re: Directionals switch
 

The advice about bad grounds is wrong. You are suddenly having signal problems front and rear….. did all the grounds go bad at the same time? And those bad grounds work ok when you apply the brake lights?

I think you are correct to assume the problem is in the switch. The brake wiring is routed thru the signal switch. When turn signal is activated, the brake light is interrupted. That much is working. But the signal circuit is not coming on. I don’t know why. You could try to dissect the switch if possible.

Re: Directionals switch
 

Here is a wiring diagram that may help. Note that the switch body needs to be grounded to the steering column. One of the fellows in our car club thought it would be a good idea to put a wrap of electrical tape on the column before he installed the switch, to prevent scratching the paint, then wondered why the signals didn't work.

Re: Directionals switch
 

O.K. it would have helped if you had let us know in the beginning of your post that the unit was working a year ago. So how old is this unit? how old is the flasher? Have you used a test light to see what wires have power or don't have power when using the switch? Have you checked all the grounds to see if they are clean? So it sounds like the car has not been driven for some time, due to the fact the last time the signals worked was a year ago. I think we need more information.

Re: Directionals switch
 

I guess this wasn't clear enough: "At one point they were working, but are not working now. So, assume the switch is wired correctly. All the other lights function correctly - parking lights (front and rear), and brake lights."

I'll try to be more specific in the future.

Re: Directionals switch
 

It could possibly be the flasher.

Re: Directionals switch
 

probably not the flasher unit at this point ... "We replaced the flasher unit with the same part, and still nothing." We are heading out to check the switch body to ground, and then the switch connections themselves when the lever is activated. I am unconvinced that the wiring is wrong, and think there is something going on with the switch itself. Either way will be pleased to find the answer. Thanks all, will let you know what we determine.

Re: Directionals switch
 

In your first post you indicated that the unit was hooked up to the tail light circuit for the signals. To begin with it is supposed to be hooked up to the stop light wires on each side of the car. Your brake switch wire is routed through the signal switch. The tail lamp circuit is not part of the signal switch. They are part of the headlamp circuit and controlled by the headlamp switch. Follow the diagram posted by 51woody to double check your wiring.

Re: Directionals switch
 

Re: Directionals switch
 

Some times the bulbs do not have enough resistance in them to operate the flasher.
I had this issue with my turn signals, The filament on American made bulbs was twice the size of the foreign made bulbs.

Re: Directionals switch
 

It's a bad ground! One of the lights is grounding through the light on the other side. When that light is energized, that ground path for the other light is lost and that light goes out. Learned that ages ago!

Re: Directionals switch
 

Well Son of a B...! It turns out the fuse block has two spots for a flasher unit. Moved the flasher unit to the other spot and it all works.

We blame an ex-boyfriend. Apparently he had been working on the car trying to get the spotlights to work and was blowing fuses - and had taken out the flasher unit and put it back in - in the wrong place.

Freaking guy.

Now we need to trace out the wire from the other flasher spot - not sure what that might be for.

Re: Directionals switch
 

I did that same dumb thing one time on a '58 Chev with an aftermarket fuse block. Can't blame anyone else, I did it. I had plugged the turn signal flasher into the flasher cavity for the four-way emergency flashers, which didn't exist on this car.

Re: Directionals switch
 

From what you described; the power from the flasher isn't getting to the switch or there is a problem inside the switch.

I would remove it from the column, take it apart, and check the wire as close to the switch as you can get.

I've found internally broken wires, loose solder joints at the switch, internal corrosion, and broken internal parts.

I don't know this actual switch or it's age; but on many older ones the switches can be opened by unbending the tabs and being careful of springs, balls, and contact plates be cleaned up and rejuvenated.

Re: Directionals switch
 

Thanks for letting us know the cause of the problem and the fix...