Electrical issue, please help

[dsblack]

Ok,
I am so tired of this. I have been working on this thing for the last month to get ready for vacation.
Now a week or so ago the truck was dead one morning. I had been working on it so I though I had left a light on or something...
Then it went dead again. I changed the voltage regulator. It went dead again, but the VR was warm. So I changed it again... http://www.oilburners.net/forums/showthread.php?t=17703 And the wires were ok.

When I changed it the last time I threw a new alternator on the truck. Now it is dead again. and the alt. is warm.

I have something going on here. How do I fix it. If I hold a wrench to the front of the alt, it pulls it to the pulley, If I unplug the 2 wires on the top, it lets go.
Sounds like a VR, but it has to be something else. What is the next step? Is the harness from the VR to the ALT something I can buy?
We are leaving this week. if the truck will take us....

 

[Agnem]

You definitely have something keeping that field current energized, and if it is doing it at rest, it is probably overcharging your battery like crazy when your driving. I'd definitely continue to do that electromagnet test everytime you shut down, and disconnect the wires so as not to drain or melt anything if it tests positive. These systems are fairly simple from an electrical standpoint. You just need to get someone (and I'm not suggest you can't) who knows electrical stuff to look at it. Somebody needs to take the time with a volt/ohm meter and check everywire and each component for shorts, or malfunctions. It sounds like your field current is staying turned on by the voltage regulator, and you either have a short in the VR, the connector, or somewhere else.

 

[icanfixall]

Replace the voltage regulator but this time disconnect BOTH positive battery cables first. A small mom & pop shop for alternators told me this will keep the system from burning out the new VR with a sudden charge when you plug it into the system. It worked for me. As posted your field is staying on charge when the alternator is stopped. That will drain the batteries because nothing is stopping the current flow from the batteries. The VR is kinds like a check valve allowing amps an voltage to flow one way if its working properly. Also the diode bridge in the alternator is another place to check too.

 

[dsblack]

I tested voltage at the regulator.

There is power all of the time at the F and the A.
The power comes on to the I when the key is turned. Did not get anything from the S.

Any ideas?

 

[icanfixall]

Have you noticied anything happening to the ignition switch lately? It may be keeping power on to some of the circuts in it. Its not very costly but kinds hard to install and set.

 

[dsblack]

No issues there. seems to be ok. The only thing I noticed, is that before all of this, and until now. the alt gauge bounces when it feels like it, does not depend on bumps or anything.
And I do get a new voltage to the VR when I turn the key on. Testing it with a light, will go and check it with a meeter.

 

[icanfixall]

The main supply bundle of wires from the dash to the voltage regulator is hidden beside the passenger side battery up against the fender. Remove that battery and have a look at the wiring harness. Mine shorted out back there years ago and the trans went into limp home mode. Its a real bad place for wiring thats for sure.

 

[dsblack]

What am I looking for? When I installed the last VR I looked at that and the bundle was in tact.

 

[icanfixall]

You have to remove the battery to get at the area I'm talking about. Unwarp the harness and loong for damaged wires. The battery acid that sometimes gets down there destroys the plastic wire case causing a short. If you don't find any problem be sure to tape up what you have removed. Don't just leave the wires exposed to everything. I really can't think of what else to look for. The electrical field isn't my best subject to work on.

 

[dsblack]

I will go and do this.
It is not my best either, and I do appreciate all of the help.
If we can not get this I will take it to a garage in the morning....

 

[Agnem]

Perhaps someone can confirm this, but to the best of my recolection, you should not have any voltage at F when there is no voltage at I. Basically what the voltage regulator is supposed to do is control the field current, which in turn controls the stator output. If an alternator gets warm with the VR disconnected, then I would presume the rectifier diodes are bad in the Alternator.

 

[dsblack]

Alt. cooled when unplugged. I do not have voltage on the pin inside the alt. with the VR disconnected.

sounding like another bad VR?

 

[dsblack]

If I take an ohm meter to the VR I get 0 between the F and A. .7 Mohm when using any of the other plugs.

 

[typ4]

there should be no voltage at the F connector until the key is on, A should be battery voltage I is ign power S is stator,. only power on it when charging.
The f wire goes to the reg and alt only, I goes to the ign switch .S goes to the reg and alt only. Unplug the harness at both ends and see if the plug still has power . I bet you are having a run of bad parts, go to an auto electric shop, wish I was closer we would fix it right up., tell you what you come put the fuel pump in the minivan and I will fix your electrical stuff,


After reading the last post you do have another bad reg.

 

[crabbypaul]

Please bear with me as I have never posted before but I had this problem when plowing snow 2 winters ago. What I had was a bad gronnd to the plate on right inner fender you can confirm this by measuring the voltage drop between voltage regulator case and negitive battery cable end. It should be almost 0volts or under .1volts. If this was your problem your voltage regulator will need to be replaced again something happens to the transistors and it puts voltage to field all the time.