Packard Forum Index » Post-War (1946-54)

omg.. i just typed out so much stuff.. and my "session" timed out.. anyway..

"solenoid power" wire connects to the "right" post on the starter solenoid..

"ign switch start" connects to the "S" post on the starter solenoid

"alt power" connects to the "batt" post on the alternater

is this correct?
where does the pos. battery cable bolt to?
what else do i need to connect to the alternater?
the ballast resistor goes where?

i cant remember my other questions right now..

oh yeah.. i'm using a harness from ez wiring..

What year and model of car are you inquiring about? I see ballast resistor so if original, I'm assuming you asking about a 55 or 56. Where the positive battery cable does depends on which year as 55 is positive ground and 56 is negative, unless of course someone changed it over. Or is your car a 6 volt car converted to 12 volts?

I did this diagram for the 51-53 cars, but it is applicable to all cars with the exception of the carb starting circuit.

This assumes you are using a standard GM 3 wire alt.

Attach file:

---

  (18.36 KB)

BigKev:

1. So, if I want to use a conventional ignition switch (with "Start" position) in place of the Packard ignition switch, I just bypass the carb switch, right?

2. What does the dashboard "battery light" do when you are running an alternator? When does it come on? I notice you have it wired to the "accessory" position.

Jim G

Jim,

If you are using a conventional 4 position start swtich "Off-Acc-On-Start", then you would ignore the carb starter switch, and run a wire from the Start position on the 4-pos switch directly to the trigger terminal on the starter solenoid (small terminal).

The GEN light (if you have one on your dashboard), is the light in the diagram (also called an idiot light). It is hooked to the ON or ACC position on the starter switch. Basically the way it works, if you turn the switch to On or Acc (depending on how you hook it up), and the car is not running, then the GEN light should light up as the Alternator is not producing voltage equal to or greater than the voltage seen at the ACC/On postion. So the current flows from the swtich, through the light to the alt and the light turns on.

When the alt is producing voltage that is equal to or greater than the voltage seen at the switch, then the light goes off. If the GEN light comes on dimmely when the car is running, that mean the Alternator is producing voltage, but at a rate that is lower than the voltage at the switch. This mean either the Alt is not turning fast enough (low rpm), or the alternator or regulator is going bad.

A GREAT explanation, BigKev. Thank-you.

Jim G

A word of warning if I may.

The diagram appears to show the alternator "Field" terminal connected to battery power. This will work, but is not a good idea.

If a standard alternator is connected this way the field will be energized all the time. The wasted current will slowly discharge the battery, killing it in a week or 2.

The correct way is to connect the field to keyed power. In other words the "On" terminal of the key switch.

It is possible to get around this by using a "one wire" alternator. This is an alternator with a special voltage regulator made for diesel tractors, dump trucks etc. It is called a "self exciting" regulator.

There are a couple of drawbacks to this alternator. One is, it is slightly more expensive. Another is, that sometimes it does not kick in until you rev the engine to 1800 or 2000 revs. As long as you are aware of this and keep an eye on the amp gauge you can stamp on the gas pedal and get it going. O ya, you have to run an amp gauge or volt meter because it has no gen light wire.

On the whole it is best to just wire the field to keyed power and use a car alternator.

Rusty, good point and I agree with what you say. From the little I've read about it, another issue with the single wire alternators is that their output (at least those that I've seen specs on) is only marginally more than generators. I supose there are exceptions though.

Not sure that is true about terminal 2 (Voltage Sensing Terminal) on a GM 10SI alternator. If just did a quick look through the various diagrams on the aftermarket wiring company websites, and I also looked at the factory wiring diagrams for several 1970's GM cars, and they all have terminal 2 hooked to a always-on 12v source.

Most people just bridge the terminal 2 to the batt terminal. Why this will work, it is not recommended. The purpose of Voltage sensing wire is to get the actual voltage reading from the main harness. The voltage at the alt batt terminal, or the battery itself may not be representive of the voltage at the main harness junction due to wire resistance because of wire length, connections, etc. The main harness junction is where GM connected the voltage sensing wire. Which was a constant hot 12v source.

Now that being said, there is nothing wrong hooking it up to switched source as you have described. I just drew the diagram based on the GM application.

I now remember why I have the dash light wire to the ACC positon instead of the ON position. There are some instances where the Alt can feedback through the dashlight circuit and keep the igntion circuit active, after the key is turned off. Most aftermarket harness companies (Painless, Ez-Wire, etc) recommend using a diode on that wire to prevent that feed back. I thought it would just be easier to hook it to the ACC side of the switch. The downside is that the GEN light will come on when the ignition is left in the ACC position. But then again that could be a good warning that you left the key in that position.

Hope this all makes sense.

Not sure what you mean by voltage sensing. The field terminal is simply a source of 12 volt power to the voltage regulator. The voltage regulator controls the field coils, feeding them enough power to make the right amount of electricity from the alternator.

If the field is on all the time it will definitely drain the battery. It does not matter if it is connected to the battery directly, on the starter, or on the alternator it's all the same.

If you mean the gen light or idiot light it too should be connected in such a way that it goes off when the key is off.