440roadrunner

First, do you have a "book" with wiring diagram, and a meter?

I don't know if you have the older style ammeter which uses "all the current" to the ammeter with two large wires, or do you have the "newer" "shunt" type ammeter, which uses small (no.16?) wires to the ammeter

Start by reading this page here:

http://www.madelectrical.com/electri...p-gauges.shtml

On my old '70, I ran amateur/ two way radio gear in the car, and the firewall connector failed. I ran #6 wire all the way from the alternator to the ammeter and back. I actually drilled out the firewall connector for those two terminals, and just ran the wire right through!!

Here's simplified diagrams: Yours is the bottom diagram, "70 and up"

http://www.fortunecity.com/silversto.../45/charge.htm




Now, a few things. First, old as these are getting, ANYTHING can happen. Check voltage, both with engine OFF and running at fast idle, AT the alternator large nut connector. Voltage should be same as battery, and at fast idle, should be "up" from the battery voltage. With the car running on fast idle, measure with NEGATIVE meter probe on the POSITIVE battery post, and POSITIVE meter probe on the alternator nut connection. There should be very little reading, may 1/2 volt, if charging hard, maybe as much as 1 volt. ANY reading upwards shows problems with the large wire going from the alternator, through the firewall, to the ammeter, back through the firewall, and to the battery. SUSPECT either the firewall connector or the ammeter itself. These commonly melted the plastic around the meter in the dash unit, causing the connections to loosen.

Also, (at least on B bodies) somewhere up near the ignition switch wiring, there is a taped up "in harness" Y splice. I've found two cars in my lifetime with these broken.

Now, say, the first test is "OK" that is, you have battery at the large connector.

Now you want to try and "full field" the alternator. Disconnect the regulator connector (at the regulator) Pull both small wires off the alternator. Take your meter (to ground) WITH THE IGNITION in "run" find which wire has +12. I've forgotten the color. Take the wire which is "hot" and hook back up to the alternator. It does not matter which one goes where at the alternator.

Now, take a clip lead (test lead) and clip to the remaining "spade" (field connector) on the alternator. Ground the other end. You should see a small spark, if not in bright sun. Start the car, and the alternator should charge "full current." Don't do this for long, the voltage will really climb if you wind up the engine. You should hear the alternator grunt and whine, if the ammeter is working it should charge. TO BE SURE, measure both the voltage (to ground) at the battery and at the alternator "nut" connection. They should be close to the same voltage, not more than 1/2-1 volt AT THE VERY MOST apart.

If this doesn't work, you may

still have a wiring problem

have bad brushes in the alternator

have an open field in the alternator

have other problems in the alternator, such as bad stator or bad diodes

If this works, recheck or replace the regulator, check the connector for continuity. One field wire should go directly to the "right hand" connector on the regulator, and the "left" or "center" pin should go to the other, and be "hot" with the key on.

Also, as with above, hook the alternator up "normal" and try grounding the field at the regulator, which will verify that

The alternator field is getting +12 through one lead, and the wires are both good up to the regulator. Make sure you ground the correct wire, look at the diagram. Ground the one which does NOT go to +12

If this doesn't work, but DID work when you "full fielded" the alternator, you have a wiring problem from the alternator to the regulator, or from the regulator to the +12 connection


CHECK that the regulator is GROUNDED. Scrape away the paint, and use "non rusty" bolts preferably with toothed (star) lock washers.

A few things:

If you have large wires going to the ammeter, you have the old "full current" ammeter. I can't stress enough to check, check, and recheck the firewall connector. ALL CHARGING CURRENT, ALL OF IT goes through that firewall connector TWICE.

If you have the old style ammeter, check the dash unit CAREFULLY. The slightest looseness of the wire connections shows that the plastic has melted near them and allowed things to get loose. At least some of these ammeters were held together by the very nuts that connected the wires. That meas that if the plastic softened, the wireing connection would loosen.

If you have the newer "shunt" type ammeter, they work more like a voltmeter. They "tap" a sensitive meter movement with fine wires across a section of the car wireing itself, and "measure" the "voltage drop" across that length of wire.

JUST ABOUT ALL shunt ammeters, including the ones in the Fords I've owned, my little Ford Ranger, and my friends later Mopars, are PIECES OF ILK. You all know what "ilk" is. It's bad. Real bad.

The reason? They are "numb." They are "insensitive" and don't show much. God, you have to be charging up a storm for them to show anything at all.

Here is a better diagram:



In the "full field" test you would pull the green wire (in this diagram--yours may be different) and ground the spade at the alternator.

Don't be afraid to "suspect anything."

Just because you bought a new regulator does not mean it is good.

ALL wiring is suspect, especially at the age of your car.

440roadrunner

So far as the blue and brown, my '70 book shows different. However, yours has electronic igniton.



My '70 book shows blue going to

one side of the ballast
one side of the alternator field
one terminal on the regulator

All these are tied together and end up back at the igniton switch



That splice must be buried somewhere in the harness before it gets to the firewall plug I don't remember how your harness is laid out, so all you can do is look at it and gently cut into the tape here and there. If you see several "blues" then you know you have to get closer to the firewall.



You still may have a problem. First thing to do is get a known good, fully charged, battery in the car, even if you have to "borrow" one out of another car, then check the charging voltage.

HOWEVER you might still have a problem. If the wireing in the regulator circuit has a poor connection, the regulator might try and compensate. Here's why. I'm speaking generally, here, not just of your car. Wherever a regulator gets it's "sensing" voltage from the battery, it will regulate voltage based on that sensing voltage. That means that if the wiring in the "sense" lead has a resistive connection, the voltage regulator will "see" lower voltage than what the battery "really" is, and because the regulator "thinks" the voltage is low, it will jack up the field to the alternator in an effort to "get the voltage up." I would go through ALL connections in that regulator circuit. Clean them with some sort of wire brush or sand paper.

You MAY also STILL HAVE a bad regulator, so:

1: Try a known good, charged battery

2: Clean the terminals and inspect the wiring

2a: Make SURE the battery main post is grounded to the
block, and that you have a sizeable jumper (no 10 or
bigger) from the block to the firewall near the
regulator.

3: If the voltage is still high (battery will probably gas
bubble, and smell. Replace the regulator.


I wish I could meet some of you guys. I'm getting old--nearing 60--and have some health problems. I've spent a lot of time "back in the day" with several of these cars. Other than body work, and precision work, like, rebuilting automatics or power steering pumps/ gears, I've done all my work. I used to know these cars inside and out. I could teach you a lot in just one afternoon.