Packard Forum Index » Pre-War (1899-1942)

Good going Don. Getting her out for a drive must have been pretty exhilerating! Especially with all the history you have with the car. Chris.
P.S. I got a real chuckle out of you relating your stories of playing gangster in the car as a kid with your friends and someone being the getaway driver'! LOL My Grandmother had an old '28 Model A Ford in the 'back 40' and we did very much the same thing with it, 'steering' and shifting gears like we knew what we were about! LOL

I still do that at 62, isn't that why we have these old cars!
Bob J.

I have to say, just sitting behind the wheel, really brings back those memories as a kid. I can’t even explain how good it felt to actually drive it. Amazing.

Last night, I played contortionist and got the ammeter re-wired. It reads the right way now!

I’m super excited for tomorrow. We’re supposed to have beautiful weather. All of my wife’s family is coming over and I’m planning some short Thanksgiving day cruises around town. Going to fill up the limo!

Okay…I’m back to the original problem that had me questioning the generator. I have since confirmed that the generator is working well and charging as it should.

When driving at night, after about 5 to 10 minutes, the lights start flashing on off…somewhat randomly.

Since it is all of the lights…ie everything connected to the light switch and nothing else electrical, I believe the issue must be with the light switch itself.
To clarify, the headlights, tail lights instrument lights all blink). The dome lights and other electrical items continue working fine.

Could it be something as simple as the contacts being dirty resulting in the vibration of the car making and breaking contact? I can’t think of what else it might be.

Thoughts appreciated.

While you could have an intermittent short somewhere in the light wiring that is tripping the switch protection, the mostly repeatable on/off symptom after a few minutes of operation is also very typical of a weak circuit breaker. As circuit breakers age they tend to change characteristics, usually tripping at a lower amperage than their rating. This is often seen in postwar models and while most earlier models use what Packard called a thermostatic overload relay which is an integral part of the switch, it operates very much like the later breakers. Current flowing thru a bimetal strip heats the strip and the more current, the hotter it gets until strip bends and opens a contact.

There is an adjustment screw for the earlier strips although to get an accurate adjustment special equipment is required and Packard says the adjustment should not be changed. This is probably due to dealers not having the equipment to measure and vary the current thru the switch. I don't know how easy it is to access the switch and adjustment screw in the car. If you do not find any short, you could try another switch as Packard recommends or if the switch and screw can be accessed maybe go ahead and try to move the screw a tiny bit one way or the other and see if the problem goes away or gets worse. As I recall, the adjustment screw looks like a small slotted setscrew with a nut on it. The screw will be electrically hot so be sure to disconnect the battery between adjustments.

It will not take more than a very slight amount of adjustment so if you do try, only go maybe a 1/16 to 1/8 of a turn and keep track of the amount and direction so you do not get it so far out current protection becomes worthless.

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Thanks. This is very helpul. I am pretty confident that. I don’t have a short anywhere. All of the wiring is new and in very good condition. I’ve also, gone back through it several times to make sure.

It sounds like the thermostatic relay is likely the culprit.

Do you know which way the adjustment screw would need to be turned? It sounds like I would need to adjust to allow a little bit higher current.

If it is the thermostatic relay, then I think it isn’t far out of adjustment since the lights don’t stay off for any longer than about a second each time they go out.

This would also seem to explain my first experience with this. The lights started blinking. Then, I stopped for gas and turned the car and lights off while getting the gas. Then, the lights worked fine right up until about the time I got home which was again right at about five minutes. Stopping for gas was probably long enough for the bimetal strip. To cool off completely.

I don't know how your switch and adjustment screw is configured to suggest a direction.

If the adjustment screw is actually part of the contact connection then screwing it down or extending the screw end would cause the bimetal to put more pressure on the connection so more current would need to flow for the bimetal to raise it off the contact.

If the screw is positioned a distance away from the contact and not part of the connection but screw is pushing against the back of the switch to hold or prestress the bimetal that would normally be pushing hard against the contact then it would need to be loosened or end raised so the the bimetal would want to push harder against the contact.

Thanks, Howard. All very helpful.

Looks like I have small “project”. In any case, I’m pretty confident that this is the issue based on your information and how it’s behaving.

I suppose that as a last resort, I could bypass the thermostatic relay with a fuse. Hopefully, I it won’t come to that.

I've had the headlights on/off issue with old 1960s Ford pickups with halogen headlights added. No problem on dim, but extended bright operation would get the on/off cycle going. Opening a window or kick panel vent would eliminate the problem A new switch helped, but the problem would still happen in hot weather or sitting still.

Putting a bypass resistor in parallel with the breaker would cure the problem, but the trip point of the breaker would then be higher, perhaps too high.

Any resistor used would have to be able to stand high heat and be mounted in a safe manner. A replacement style ignition resistor might be suitable, or 2 or more of them in series. They're typically about 1.5 ohms.

Anything that allowed higher than normal system voltage,such as an out of adjustment regulator, might aggravate the problem, as would anything that added higher current demand, such as higher wattage headlights/tail lights or added driving lights.

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If you decide on that approach, I would recommend against using a fuse because if it blows you are dark until the fuse is changed. Get a 30 amp type I (one) self resetting circuit breaker instead. This stud type breaker mounted on the back of the headlight switch is what was used in later years. If you buy a breaker having attached mounting tabs with screw holes, it would be easy to extend wires and mount the breaker a short distance away from the switch. Issue would be connecting it. One side of the new breaker would go to the switch battery terminal connection but since there is no provision on the switch bimetal contact for the side going into the switch you would have to come up with something. You would also want to somehow disable the original protection so the two are not trying to work in parallel.

Here is a Napa offering but the breakers should be available online and at most parts stores.

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