turn signal and brake light woes

[pkingco]

Hi all. I'm close to putting the 59 convertible on the road (plates are on the car!). But I'm having trouble with the turn signals and brake lights. I had turn signals working before, but now I get nothing on either side. Parking lights/tail lights/headlights all good. I checked the fuse on the light switch: good. What procedure should I follow to hunt down the problem?

Re: the brake lights, I have only the passenger side working now. Both were working before. And the brake light(s) stick on when I release the pedal. I have to remove one of the wires on the brake light switch to turn them off. When I reconnect the switch, lights stay off.

Any thoughts on these issues would be greatly appreciated, as always.

[jopizz]

It sounds like you have multiple problems. The sticking brake lights could be the stop light relay in the trunk. I would check that first. I doubt it's the brake light switch since the lights stay off when you reconnect it. Your car as two different brake light circuits. The inner lights come right off of the relay and are tied together. If one light doesn't work then it's either a wiring problem to that light or a bulb/socket problem. The outer brake lights are independent of each other and come off of the turn signal switch on separate wires along with the turn signals. If the turn signals don't work at all check the flasher first. If that is good then you may have a turn signal switch problem. Do the turn signal lights come on at the instrument panel and stay lit? As always follow the wiring diagram.

John

[pkingco]

Thanks, John. The turn signal lights do not come on at the instrument panel now. They did both work. I'll check the flasher and look for that brake light relay.

[pkingco]

Well, the driver's side bulb socket had a bad connection, so that solves the one brake light. But I need to correct my previous observation— the brake lights do not turn off when I cycle the connection to the switch. They come back on when I reconnect it. I checked for a relay in the trunk, but do not have one.

Re: the directionals, I removed the flasher and tested it, and it is working fine. I removed the fuses on the light switch and tested both for continuity and they are fine. I tested for power from the orange/yellow wire that runs from ACC terminal to the flasher, and could not get a reading. But the orange/yellow wire is connected solidly to the ACC terminal that also has radio and heater, which both work. Seems unlikely that it is a bad wire, since directionals were working fine before.

Any further thoughts?

[jopizz]

But I need to correct my previous observation-the brake lights do not turn off when I cycle the connection to the switch. They come back on when I reconnect it. I checked for a relay in the trunk, but do not have one.

It sounds like your brake light switch is bad. Either that or your brake push rod is adjusted too long.

Testing the orange-yellow wire is pretty simple. Remove the wire at the light switch fuse and test it with your voltmeter. That's the first point of contact after the switch. If no power there then it has to be either the wire or the connection at the ignition switch. It's important to isolate the wires from the light switch and flasher so you are not introducing more points of failure. Don't assume anything. Trust your meter and work your way from the ignition switch to the light switch to the flasher. Unless it's a new harness broken wires are very common after 65 years.

John

[pkingco]

Thanks, John. I do have all new wiring harnesses, but I will check that. Re: the brake light issue, is it possible to adjust the brake push rod without dropping the pedal assembly? A simpler test will be to test the switch, but I am suspecting the rod.

[jopizz]

There's an eccentric adjuster on the pedal to adjust the push rod. Refer to the diagram.

John

59 brakes.jpg

[pkingco]

Thanks, John. The clutch pedal in mine complicates things. I can't see any way to get to that eccentric without some dismantling. Will see if I can sort it out.

I got the directionals working. It turns out the new harness bypasses the light switch with an inline fuse holder. Fuse was blown.

[jopizz]

I would just put an ohmmeter on the brake switch and loosen it. If it stays shorted then it's not the push rod.

John

[simplyconnected]

Be careful with the brake switch wires because one is always hot. Pull one of the wires off the brake switch and see if your stop lights go out.
(We commonly short both brake switch wires to test the lights to simulate someone standing on the brake pedal.)

With the wires off the brake switch, if your stop lights don't go out, they are getting power from another source.
If they do go out, something is energizing the brake switch or it's a bad switch as John said in post #5.
Did anyone work on the Master Cylinder? - Dave

[pkingco]

Thanks for that, Dave and John. Still having the issue with the brake lights. I replaced the switch—path of least resistance—and the lights still stay on after depressing the brake pedal. But only when the car is running and pressure builds up in the system. I can pump the brakes all day before starting and the switch works fine... lights come on and off. So I'm quite sure the issue is the rod length. Because reaching the eccentric bolt is going to require removing seat, the lower dash trim panel, which in turn requires removing the overdrive cable from the manual transmission and pulling it out completely (because the replacement cables don't have any way to remove the lock nut at the end of the cable to free the trim panel), and lowering the steering column to see if I can gain access, I'm first going to try an experiment. I'm going to shim the back of the master cylinder out and see if that solves the problem. If so, I will know it is the rod length.

If you have any other thoughts, please let me know. Many thanks.

[pkingco]

Well, I ended up removing the seat, dismantling the console and under dash valance and loosening the steering column to see if I could gain access to the eccentric bolt on the clutch/brake pedal assembly, but to no avail. So I followed the tip Dave provided me with (Thanks, Dave!) and made a bracket for a momentary switch and installed it on the brake pedal arm. It just comes into contact with the under dash booster when the brake pedal is depressed and brake lights now work like a charm.

IMG_3779.jpg

[jopizz]

You have to wonder why Ford didn't do that in the first place. It's certainly more reliable than the hydraulic switch.

John

[simplyconnected]

...which begs the question: Is your master cylinder's piston retracting far enough for brake fluid to return to the reservoir? If not, you stand the chance of having your brakes lock up. When DOT-3 gets hot it expands, exerting more pressure on the brake shoes and in turn it turns the brake light switch on.

I love the idea of a mechanical brake light switch on the pedal. If you aren't running the current through relay contacts, I suggest you do so. You can keep the setup you have but let the switch turn a relay coil on. Then, let the relay contacts control your brake lights. Your switch will never burn up from overcurrent. This is how I was able to use a computer mouse switch to run my lights. - Dave

[simplyconnected]

Finally... a solution to the confounded brake light switch problem:

image.png - Dave