Ford 3600 charging system

Curt Cooke · Nov 11, 2014

Need an education. 3600 with Q cab. Battery is dead after sitting a few days. I determined that there was a constant draw by using a test light between the pos. battery post and the disconnected cable. The draw persisted as I disconnected and tested things. I removed fuses one at a time until I pulled the one that made my test light go out. I think it's identified as alt/field, though it's hard to read. Now removed, everything works and there's no draw. What is this circuit's function? What is the cause of the problem? Help?
CC

Bern · Nov 11, 2014

I'm assuming a Motorola charging system here with an external regulator? If so, try unplugging the regulator and see if your draw goes away. Also try disconnecting the alternator output wire. Report back with findings.

JMOR · Nov 11, 2014

" I removed fuses one at a time until I pulled the one that made my test light go out. I think it's identified as alt/field, though it's hard to read." On my diagrams it is a 5A fuse between Ign acc. and the 'I' terminal on the VR.

Curt Cooke · Nov 11, 2014

Best I recollect my procedures. Battery dies. I check and find that with the key off, I find current at the field terminal of the alt. I figured that wasn't right so I purchased a new regulator. Installed the new regulator same condition existed. Disconnected the regulator and draw ceases. Reconnect the regulator, disconnect all wires from the back of the alternator and still a draw. Hook everything back up and start removing fuses. As I said, when that last fuse was removed, the draw ceased. With the fuse removed, everything that was functional before is still functional. The alternator output is at 14.4. Does that help?

Curt Cooke · Nov 11, 2014

Replied but to myself. Please read post

sunbeam · Nov 11, 2014

I don't think that fuse should be hot with the switch off.

Bern · Nov 11, 2014

I'm thinking your key switch is mis-wired. Go here to check out your key switch wiring: http://forums.yesterdaystractors.com/viewtopic.php?t=1167553&highlight=

Curt Cooke · Nov 11, 2014

I'll re-visit that. I did install a new switch recently and did have that diagram in my hand when I did it. I'll do it again but I don't think that the colors and number of wires is the same as the diagram. I have discovered a whole lot of things different on this tractor with a Q cab than those without. Many thanks,
Curt

sixbales · Nov 11, 2014

Curt,

There's a diode in the circuit from the battery to the alternator output terminal. It's shown in your wiring diagram, but it may be internal to the alternator. I don't know where it is.

It's purpose is to prevent backflow from the battery through the alternator when the tractor is off.

RodinNS · Nov 11, 2014

The only way I ever install a new switch is with a meter... and use the audible continuity function to beep out what connections are what on the switch... Find the infeed blade and determine the rest from there. There's a few different versions of the switch so they're not all necessarily the same...

Rod

Curt Cooke · Nov 11, 2014

Does anyone know the purpose of the fuse?

JMOR · Nov 11, 2014

(quoted from post at 15:47:00 11/11/14) Does anyone know the purpose of the fuse?

urt, I guess that "know" is the key word, but like most fuses, likely to protect the wiring from too much current & possible resulting electrical fire. In this case in the feed to the VR. Is this of any help?

Bern · Nov 11, 2014

Check to make sure that you have only one wire that is hot all the time. This should be the battery feed wire.

Rod is correct, there were different versions of key switches, however the one I referred to is a pretty popular style. If yours looks identical, use it. If the wire colors don't match up, then do what Rod suggested.

Bern · Nov 11, 2014

The diode shown in the wiring diagram is not what you think. Its purpose is to light the air cleaner lamp via the oil pressure sensor when the key is on and engine is off to serve as a bulb check.

Yes, there are diodes in the alternator as you describe, but these are not shown in the Ford wire diagrams. In most Ford diagrams, the alternator is shown as a simple circle with wires going to it.

Bern · Nov 11, 2014

Here's a couple of images that may help. Again, this assumes a Motorola charging system.

sixbales · Nov 12, 2014

Thanks Bern,

Too complicated for me! My air cleaner light does come on when I turn the key to the "on" position and goes off when the engine starts (I do not have an air cleaner sensor).

The wiring diagram I referred to is from my I&T FO-41 manual for a 3600. It shows a single diode in the line between the battery and alternator. No other connections in this line. The diode is identified as the "output diode". I have no idea where this diode is located. May be internal to the alternator??

JMOR · Nov 12, 2014

(quoted from post at 08:24:05 11/12/14) Thanks Bern,

Too complicated for me! My air cleaner light does come on when I turn the key to the "on" position and goes off when the engine starts (I do not have an air cleaner sensor).

The wiring diagram I referred to is from my I&T FO-41 manual for a 3600. It shows a single diode in the line between the battery and alternator. No other connections in this line. The diode is identified as the "output diode". I have no idea where this diode is located. May be internal to the alternator??

ixbales, that Motorola 'isolation' diode is in the diagram that I posted also,, near alternator in lower left hand corner about the #56. Physically, it is on the back of the Motorola alternator, electrically following the 6 rectifier diodes & carries the full alternator charging current.

sixbales · Nov 12, 2014

Thanks JMOR,

That clarifies this issue. I don't have a Motorola alternator.

Ed Fulton

Curt Cooke · Nov 12, 2014

JMOR, nice diagram. Any chance you would have the legend to go with it? Anything you could fax?
Curt

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