Is it the Alt. or Volt. Reg. ?

[64conv65hard]

Need some help on charging issues. Coming home last night from the White House after HBO filming with the 65 Valiant I noticed the Amp meter on discharge. Put my meter on the battery when I got home and sure enough, not charging. I've upgraded to the elect. volt. reg. a few years ago and new alternator at that same time. What are the test procedures to determine whether it's a bad voltage regulator or a bad alternator? Thanks.

 

[kt340sport]

Usually if the regulator is bad , needle will not fluxuate back and forth, stays it the middle , prob brushs are bad in alternator , you can change them on the car i would take one out have a look all you need is 1/4 socket and nut driver , you could buy them in apackage of two , when i was doing auto parts.

 

[TrailBeast]

If your alt is a dual field (Three wires connected to it) ground one of the field wires to the alt case and if the alt is ok it will go to full charging output.
The easy way to tell is that it will pull the engine idle down, and the whine from the alt will get louder.
Don't rev it while doing that though, cause you could blow something from overvoltage.

Just ground a field terminal to the alt case and see if the idle drops.

If it does then it's the regulator.
If not, then it's the alt.

 

[67Dart273]

Uh....................no


It's important to understand how these work and they are actually fairly simple

Here's the simplified diagram:

(came from here
http://www.mymopar.com/index.php?pid=31

These are INcorrectly called "dual field" correctly called "isolated field."

1 In the diagram, notice the top field TERMINAL has a blue/ white wire connected. This is UNfused "ignition run" power which comes from the firewall, same wire supplying the regulator IGN terminal and the IGN system from the key

This wire is HOT in "run" DO NOT GROUND IT

2 Notice the bottom field wire, green, going to the regulator. This is the "control" --the regulator controls "the amount of ground" so to speak on the rotor, which controls charging.

So the field is supplied 12V from the key, (blue/white) goes through the rotor, and controlled by the regulator (green)

3 For a QUICK check remove the GREEN wire and put the key in "run"

Hook a clip lead from the alternator terminal you just unhooked to ground. TAKE A test lamp or meter and measure the blue/ white terminal AND the output stud. You should have battery voltage at BOTH points

4 Start and run the engine, slowly bring up RPM and look for a charge increase.

IF this happens, you either have a bad regulator, or a wiring problem in the regulator circuit

IF no charge...................

With the test setup in place and the engine running, measure voltage at the output stud of the alternator. IF the voltage is low, below 12v,

5 Recheck voltage at the blue/ white field wire and recheck that the disconnected field terminal is still grounded. If no output can be measured at the alternator output stud the alternator is bad

(This could be an easy, or more serious problem. COULD be simply worn brushes. COULD be something more serious, bad rotor, burned stator, bad diodes, etc.

6 IF the voltage AT THE ALTERNATOR STUD is extremely HIGH and the voltage at the battery is still low, THIS INDICATES a break in the charging line

The circuit path here is --from alternator output -- through bulkhead connector --through ammeter circuit -- back out bulkhead on red wire -- through fuse link -- to battery

Your top suspects if this is the case, is the bulkhead connector, and the ammeter/ ammeter connections

 

[TrailBeast]

Uh....................no

I forgot to add that you diconnect the terminal from the field that you ground to the alt first, (Sorry)

My point was to tell someone how to find out in less than 5 seconds, not to train the OP in automotive electrics.

But hey, maybe the OP want's to spend all day figuring it out.:read2:
I rather like getting to the point and fixing it.

 

[64conv65hard]

67Dart273 and TralBeast,
Thank you both for the info. I will post later to what I found. Again, Thanks.

 

[txstang84]

Usually if the regulator is bad , needle will not fluxuate back and forth, stays it the middle , prob brushs are bad in alternator , you can change them on the car i would take one out have a look all you need is 1/4 socket and nut driver , you could buy them in apackage of two , when i was doing auto parts.

...just looked up ones for my '72...$5 for a set of brushes...

I wish I could say I remember the needle doing funky stuff when my regulator went to full ground and my charge spiked to 18V, but I'd already bypassed the ammeter by that time.