Ford Generator Voltage Regulator Wiring Diagram

06 Dec, 2021 Post a Comment

Can someone help me with a wiring question? I have a flathead generator and the Field and Arm posts are wired to the corresponding terminals on the voltage regulator. Where does the Bat wire from the regulator go? I have it attached to the battery side of my solenoid but this is giving me constant 12v to the regulator and I also have constant 11v from my Arm terminal on the regulator going to the generator when ignition switch is shut off. any help is greatly appreciated. thanks!
Probably the best thing is to hunt down a wiring diagram for the year model of rig that the generator was intended for and go from there.
Right hand list is the wiring diagrams for various Flathead Fords.
I'd say it's best to save it to your computer and then expand it so you can figure it out better. at least for my 69 year old eyes that works better.
http://www.vanpeltsales.com/FH_web/flathead_drawings_electrical.htm

From what I see the Batt wire off the regulator runs off the regulator to a junction (on the headlight switch on 46/48) and then to the ammeter and from the ammeter to the same spot on the solenoid that you have it connected to. It looks like you just cut out the middleman meaning the ammeter.

Last edited: Sep 19, 2016
thanks but I have tried to use those original diagrams and I still cannot see specific details of generator and regulator wiring they seem very vague. can anyone tell me if I should have constant power to my regulator when the key is shut off? this is what I have because my Bat wire from the regulator is on the solenoid terminal with the bat cable.
The BAT terminal will be hot at all times, yes.
With the key off I also have 11 volts at the ARM post on the voltage regulator is this normal?
Regulator doesn't need a voltage signal from the key switch. Stuck contact in the regulator would be my thought as to why you have voltage at the armature when not in operation.
Just a reminder: Ford regulators are only for Ford generators..meaning that a Ford reg sends power to the F on gen.
GM and Mopar regs send a ground to their F generator terminal
Bat wire does go to cable side of the solenoid...it is hot all the time but the cutout relay in the regulator disconnects it from the insides of the regulator. In a stock Ford, say a 1948, along the way the same wire supplies power at the circuit breaker and goes through the inductive loop on the ammeter. The connection to circuit breaker in there is what powers pretty much everything electric. I try not to think about what is going on in there, but looking at first diagnostic steps in a manual "A" terminal shouldn't be hot with switch off...cutout is stuck is the diagnosis given.
Hello,
Could you provide the year, make and model of Generator you are using (12v Generator off of what year make and model)
If I'm not mistaken, flatheads were 6v?
I could research a schematic for you as well as how to polarize (if needed) the generator. It does make a difference if its GM-FORD-MOPAR.
If the cutout relay is stuck then the generator will be smoked in short order, and may catch on fire.
I'm running on an assumption that this is all Ford, either some '55-62 generator or fields from the same in a flathead case. if so, wiring is exactly the same as '40-55 six volt generator and regulator.
Polarizing for Ford, 6 or 12:
Polarize Regulator:

CAUTION: Follow these instructions exactly (Fig. 2)

A) Disconnect the wire at the regulator terminal marked FLD and use it to momentarily (no longer than 2 seconds) touch the wire to the BAT terminal. There may be a brief spark; this is normal

B) Reconnect the wire to the field (FLD) terminal

C) Start vehicle and check charging system for proper operation

if someone tells you to use s jumper, DO NOT! That method is for a different-than-Ford ground path, mostly Delco, and using the wrong method in either direction will BURN POINTS in there.
That's it! Bruce Knows his stuff!
Thanks guys I am really learning a lot about these old generators. I believe you are correct that the cutout is stuck and yes it started smoking. It is a 12 v because the generator was rebuilt to 12v. I took both the generator and regulator out of the car and took I to a different motor shop. The gentleman at the new shop seemed more "in tune" with olfer generators and specifically flatheads. He is going to look at it in the next day or so and let me know. I am confident that my wiring is correct and it is a regulator or generator problem. In talking to others they have had the same bad luck with a "re-built" generator and sometimes takes 2 or 3 times back to the shop to get it right. Seems odd to me but I guess anything is possible in this day and age where these machines we have are a thing of the past. thanks!
Gonna smoke some electrons...this is a long post on testing. Note the full fielding trick that separates gen and reg so you can see if generator charges with reg incapacitated.
Generator parts testing, 1953 style

Here are a series of tests for generator components from the Ford of Canada "Master Repair Manual" from 1953. They specifically apply to '49-53 vehicles, but I believe I am correct in saying that procedures apply back to the introduction of the 2-brush generator in 1937-8. The only circuitry difference is that the first couple of years lacked a proper ground wire, grounding only through their mountings.

Most of these tests involve 110 volt household electricity, presumably to force breakdown of any marginal 6 volt hardware. I am sure you are aware that this has potential danger if carelessly handled.

There are many ways to test generators without this…I will post a link to some simple tests, and many of the tests can also be done using multimeters, as detailed in a number of Ford USA books. The 110 system has the advantage of testing the breakdown points under more stress than they will see in actual service.

Equipment: The basic tester is simply a 110 volt bulb in a porcelain socket (let's try to be traditional here!) fitted with test prods; One wire goes from plug right into fixture, as normal, the other wire is terminated with a sharp steel prod, and the empty terminal in the fixture is fitted with another length of wire also with a prod or, possibly better, a big alligator clip. When the two prods meet, either directly or through a conductive path in your generator, the bulb will light. I'll leave the fabrication of prods and insulated grips for them up to you. This stuff was standard in auto electric shops long ago before electronics made such testing obsolete.

I believe choice of one of the plug poles will be marginally safer than the other, and I think I know which, but I haven't finished contemplating that and I hope someone with a sharper knowledge of 110 will step in and clarify that for me.

Next, I will paraphrase Quin the Eskimo, your Ford of Canada service rep, testing the components of a disassembled generator for electrical integrity:

The series begins with a growler test. I have no growler and can't help you there…

Next, clamp the wire from light fixture to the armature shaft rear bearing area. Jab each segment of the armature with the prod from the wall socket. If the lamp lights during this, a segment is grounded and your armature has failed its final.

Parenthetically, I understand that electricity flowing from one hand to the other in the case of your accidentally including yourself in the circuit is highly dangerous, as the electrical path goes right across your heart. Set up your test so that the parts are stable, hold your prod in one hand, keep the other hand in your pocket…that technique is used by many electricians when fiddling with live 110 for safety.

Onward…to the endplate. Clamp wire to endplate casting, prod the ungrounded brush holder. Darkness is good…

Field coil windings are tested still assembled in frame, unless trouble forces disassembly. Clamp wire to frame/body of generator, prod the field terminal. If lamp lights, field is grounded and that is not good. Field resistance is checked with a charged 6V battery, hooked with one terminal to field stud with an ammeter in circuit, other to ground stud. I do not have figures for 12V generators, but at 6V resistance should be 1 ½--2 ½ amps. High means shorts between windings, very low or no reading means open circuit.

This battery and ammeter circuit can be used again at the end of your rebuild for a final bench test of the complete unit: Place a jumper wire between field and armature terminals, run ammeter lead to ground post, other to armature. Generator should run as a motor and draw somewhere about 5 amps.

I hope I got all that right…will try to get multimeter type test procedures together soon.

I've never done this with 110…I've only done continuity lamp checks with battery voltage myself. I believe the low voltage tests will show parts to be currently usable while the 110 tests will expose functional-but-weak parts that are likely to fail in the future.

I've rebuilt a bunch of generators that were functional units when I started, but I've never encountered any of the serious problems that can occur on elderly windings. If I have something above wrong, please correct me on this! I know there are people here with much more generator experience than I have.

Ford-Merc-Lincoln remove Field wire and touch to Batt wire momentarily; most other cars, touch jumper from Arm to Batt at regulator. For cutout 3-brush Fords, jumper between two terminals on cutout.

2 links to Ford generator discussions:

Polarizing your charging system is covered in the first; note that there is one way for Ford systems, another way for Delco and most other systems. MANY people have the two confused. Be sure you are doing this using the Ford/heavy duty circuit system, NOT the Delco, as ground paths are different and smoke may result…

Both ways are in here:

http://www.jalopyjournal.com/forum/showthread.php?t=256038&highlight=generator+polarize&showall=1

Simple field testing with no tech:

Ford--clip on a jumper from A to F at reg. Revvitup to charging speed...reg is now out of service, if generator is good should produce 6 or 14 volts...or brightening of headlights if you have no meter. This is full-field test, generator vs. Reg

http://www.jalopyjournal.com/forum/showthread.php?t=278956&highlight=generator+polarize&showall=1
This is interesting info. This old time electric motor re-builder told me that the polarizing technique is not so much ford and GM but rather how the generator was built. A circuit vs. B circuit. He told once he opens my generator he would know and be able to give me correct polarizing technique. I guess this makes sense especially when dealing with rebuilt Generators
Please clarify so I understand better. Does the field wire turn the system on (closes contact from battery to armature) when the key is on ? If so, I stand corrected. Now back to OP's having power at the armature when the system is off would suggest a stuck contact at the relay ? Correct ?
Generators that have a true regulator, (not the old cars with a "cut-out")
Brief explanation on GM/Mopar, the field coils need to be "connected" to produce current, much like a starter motor needs it's fields to be connected to spin. These generators and regulators have no connection to the key switch at all.

Generator is nearly the same as a (starter)motor. Once the unit becomes a magnet, it either makes the armature spin, or on a generator, the magnetism makes the armature produce current

On most brands of generators(GM/Mopar), you can make them produce current by holding the pulley or fan behind it, on your wire wheel bench grinder. Spin it while having a voltmeter hooked to the Arm terminal, but then ground the field terminal to the case. This will cause the generator to run wild, as it is not regulated. No battery needed to make it work.
My bad for using the word regulator. I do know that a generator can make voltage on it's own and go out of control if not "regulated" which is what the cut out does. Much like early radial aircraft engines that didn't have any sort of throttle control. The speed was controlled by "cutting" the ignition out and back in again.
Once in a blue moon, if you find a generator that sat a long time...they can loose their residual magnetism that allows it to start producing current.
I'm not sure if polarizing will remagnetize that residual issue, but the last one I did, I just ran it like a motor on the bench for a moment, and it then worked great in the car. It was a Lucas 12v Positive ground, so I decided to "motor it", rather than jump it
I received my generator and regulator back from the shop today. It seems as though there was a "stuck" contact in the regulator causing constant voltage to run through the Armature post on the regulator. Luckily I caught it in time but it could have fried the generator had I not.
Bruce,
How do you adjust the regulator so it cuts out at 14 volts on a 1950 12v flathead/generator? The one in my car idles (800rpm) at 12.5, but when I accelerate it goes up to 15.5. My voltage gauge is accurate. I put a voltage meter on the gauge posts to verify it's accuracy. It's been running this way for years and hasn't damaged anything. I have an Optima battery in case that makes a difference.

With the headlights on it reads 14.5, or there about. Difficult to tell exactly with sweep hand guages.
That's why I put up the diagram as a reference at post #6. When contact is closed the battery becomes connected (contact made) with armature. I know it wasn't the right model or year but the principle is the same.
(changing voltage setting question)
From a '52 Lincoln-Merc charging system pamphlet dated 1951...general idea should work in regs made by different companies with different springs, etc.
Voltage limiter relay interrupts current when a specific voltage above battery V is reached, then rapidly opens and closes to hold that. You probably need an analog meter, since a digital one will go mad trying to read the voltage jumping from zero to too much a zillion times per minute.
You need to weaken the spring tension on the contacts by bending to get the points to open at lower V, strengthen spring pull to raise it.
Just about any Ford manual or service bulletin from about '41-55 will show you the details.
Annoyingly, temperature is important during tests...cover in place on reg, etc., and since you can'y really get that entirely right you may need to measure and re-bend with car back together and running down the road.
Couple things I have found making accurate adjustments - the battery needs to be fully charged, but then drawn down just slightly to make it charge. Cranking the starter for a few seconds should do it.
Temperature matters, and is compensated for by the regulator, but it's important to use the chart. The cover needs to be on for voltage check (though not for adjustment, obviously) not because of temperature but electromagnetic reasons, it will be different than with the cover off.

For all that it's important to first make sure that everything in the circuit is grounded well and connections at block and through brackets and such are not corroded before trying to make adjustments. These older cars and trucks are full of corrosion (or new paint) no accurate adjustments can be made unless there is low resistance in the circuit.

As far as the regulator itself it works better to lower the voltage below target and then bring it back up, by tightening the spring, similar to the proper method of tuning a guitar string.

Finally make sure there is a problem to begin with, generator circuits run a little hotter than alternators for some reason (see chart) and needs to be compensated for temperature, too.
On the grounding...Ford added the direct ground from a stud on generator to base plate of reg in maybe late 1940, greatly cleaning up the ground path. Run that, then add another wire from the reg base right to end of battery ground cable.