Generator Light - On Steady

[bcomo]

Right now my generator light is ON STEADY, no matter what RPM.


All of the connections are good and tight. I peeked into the Gen housing using a flashlight, and the brushes are good and not hung up. I hope that it's the Voltage regulator, otherwise it could be an open or shorted field coil in the generator.


I'm going to have to try to read the amps on the generator -- haven't done that before.


I see in the shop manual that the Amp output can be tested by disconnecting the Armature and Field wires at the Generator, then using a jumper wire from the Armature stud to the Field stud on the generator, then connecting an Ammeter between that jumper wire and the battery postive.


My questions are:


1. Has anyone measured the Amp output this way.


2. Can't the Amps be measured at the Voltage Regulator by disconnecting the same pair of wires at the regulator, then jumper them, and go from the jumpered pair to the battery?



Thanks

[JohnG]

You should have a (yellow) lead from your generator to the front side of your starter solenoid, on the passenger wheel well. The + lead from the battery also connects to the starter solenoid there.

I would disconnect the yellow wire from the solenoid (leaving the heavy lead to the battery as it was) and put an Ammeter in between the yellow wire that goes to the generator and and the front post on the starter solenoid.

The ammeter can now measure the current flow from the generator to the post on the solenoid as it is in series.

Once done, turn your headlights On. You should have a - (negative) reading on the Ammeter as you are drawing power from the battery to power the headlights. If it is + then swap the wires to the Ammeter.

At this point I would fire up the car and see what kind of amp readings I got. Hopefully + (positive!). If I got + readings, I would then turn the headlights on and the brakes and see if it is still positive with a substantial load on it.

If things are bad (-) I would consider another voltage regulator as a quick fix or take mine into a shop and test it. I keep a spare around "just in case", and because they are cheap.

Checking the leads to the voltage regulator (and any other critical wires) never hurts, including taking them off and polishing them up.

Checking your ground wires both to the chassis and the engine block is a good thing to do as well. I once thought I needed a new battery only to find the ground wire to the engine block had gotten loose.

Let us know if you have questions. I don't mind setting the same thing on my own car and walking you through it.

All this is pretty universal and applies to almost any vehicle.

John

[bcomo]

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[bcomo]

John:

Thanks for the detailed reply -- I appreciate your help.

I just replaced the Voltage Regulator, and cleaned all of the wire contacts. Generator light is still on steady -- no flicker whatsoever. At least that part's done.

I see the yellow wire on the solenoid stud, and understand about testing amps there. Problem is, I can't find an Ammeter in this town. Auto Zone type places don't carry them. Where do you get one to read 1 to 50 Amps? Can you suggest one, and maybe I can find it on the web.

All of my battery cables, starter cable, and chassis ground cables are brand new -- I replaced a starter 6 months ago.

Just in case, I'll re-check those cables. I'll also re-check the generator wires, take them off, and clean them too.

Anything that you can suggest will be greatly appreciated.

I'll get back with a report.

[JohnG]

hi Bart

I would still suggest taking one or both Voltage Regulators in and getting them tested. I recall Casey putting a new one on that was also defective and not having success until #3.

You can also look in the Yellow pages under "Auto Electric" and take find a repair shop specializing in generators and regulators and so on. You can take both the Regulator(s) and the Generator in and say "check 'em out, tell me what's wrong".

Having good brushes on the generator is good; there is also the Field that must function.

Do you have a multimeter so you can check Voltage?? I prefer reading amperage but Voltage across the battery with the car running is a good indicator. I believe it ought to get up to or over 14 Volts (see Shop Manual as well as older posts here).

Now, you ought to be able to find Ammeters all over the place. Most Autozone kinds of places carry accessory gauges such as Amps, Volts, Oil Pressure and so on. Those would be shiny and with brackets. Sometimes in groups of 3 so the price goes up. Having an oil pressure gauge around is not a bad deal if you get stuck with 3. I would bet Walmart has gauges. A salvage yard ought to have any number of vehicles where you can pull one out of a junk car or truck. They are universal. If all else fails, I will mail you one Monday (but I am in MA...)

John

[byersmtrco]

I test mine right at the battery. I have a little volt meter. It shows 13.5 volts at idle and about 14.5 a 2000? rpm.

[JohnG]

Yes... and I think if your charging system is in the toilet, then you only see 12 V and it does not change.

[bcomo]

The regulator checks out, and is working correctly.

Here's the problem in a nutshell --

The Arm terminal at the Regulator has to get at least 12 Volts from the Generator to make the Cutout Relay contacts (at the Batt Terminal) close. That puts the voltage to the battery and also makes the light go out.

I removed the cover from Regulator (to look at Cutout Relay), all wires still connected to regulator, and engine running 1500 RPM, I have the following:

Voltage from the regulator Arm Terminal to ground was 2.5 Volts incoming from the generator (That's not a typo -- it was 2.5 Volts). The Batt contact points were open, and light is on.

I then measured the voltage from the regulator field terminal to ground and also got 2.5 Volts (same as the arm terminal to ground volts).

So, my Generator is only putting out 2.5 Volts to the Regulator, which is why the contacts points on the regulator won't close.

I turned off the engine, and restarted it. Gunned the engine 3 or 4 times to about 4,000 RPM -- and the light went off long enough for me to take another reading at the regulator ARM terminal to ground -- 12.5 Volts and light off.

Restarted engine again -- and light is on -- and has stayed on forever since then.

The only thing left for me to measure is the voltage directly from the Arm Terminal stud on the generator to ground -- under the car, with it jacked up, and running at 1500 RPM. You know I just can't wait to do this -- don't you??

Can I ask you to take a Voltage reading for me? With your engine running at fast idle, (1500 RPM or over), and Gen light out, take a voltage reading from the regulator Arm terminal to ground. I'll bet it's at least 12 Volts.

That will answer things until I take the undercar reading.

Thanks

[JohnG]

hi Bart

I took voltage from the outer post on the Regulator which I believe is "Arm" to ground with the car running and got about 14.1 volts. It was pretty much independent of RPM although I revved it up to around 1500.

Just in case I was wrong about which one is the Arm post, I took it at the opposite one and got the same readings.

The regulator is ancient and the labels long gone so I compared it to a new, spare I keep around and also the picture in my shop manual. So I am quite sure I was taking readings from the Arm post.

While we're at it, the voltage on the middle post is about 13 or so at idle but drops to 2.5 to 3 when the engine is revved up.

Hope that helps.
john

[LuckyJay]

The syptom you describe would lead me to suspect a field coil short (at least partial). My next move would be to remove the generator and take it to "an old auto electric shop", as already suggested. BTW, the generator output can also be measured with a small inductance type meter that simply is held next to the generator output lead and you don't have to break any circuit.

[bcomo]

JohnG:

The Armarture (ARM) terminal would be the bottom terminal on the regulator.

The top terminal is the Battery (BATT). The BATT terminal votage will always be the battery voltage

Did you take the reading from the bottom terminal?

Wildcat15:

Depending on what what JohnG says -- I think that you're right about the field coil open/short. I wonder if the brush springs could be hung, but make still appear to look like the brushes are seated.

Can I remove the end bell on the generator while it's on the car, pull out the long screws, and check the spring tension?

I'm getting a small Snap-On inductive Ammeter, but won't be here for about a week.

Thanks

[JohnG]

Yes, I took the readings from the bottom post.

My regulator is mounted on the drivers side with all posts toward the front of the car (so on my left as I lean into the engine compartment from the driver's side) and the ARM one that I took readings from is the bottom one.

The brushes need to be free to move and hence exert a certain amount of pressure against the armature as it rotates. Merely touching it is not sufficient. It is possible that crap is in their holders keeping them from doing this. Can't hurt to try. I think you can do this with it in the car but won't guarantee it.

[bcomo]

JohnG -- Sorry, I see now that you said that the two outer terminals, top and bottom were the same reading.

A rebuilt generator from Concourse is $130 + $50 core + $25 shipping. I wonder if I should buy a rebuilt, or have mine rebuilt? There's supposed to be a good Generator shop about 30 miles from me. I don't know what they would charge if they have to replace the field coils along with the usual stuff to rebuild one.

[JohnG]

hi Bart
If it turns out the generator is faulty, I would urge you to get yours repaired vs a rebuilt. My reasons are: a) you take the regulator and the generator in and they do what is needed to produce a functioning unit (pair) b) they are there if you have problems down the road c) they will warranty their work. Usually these are old-school people who know their work well and take pride in it. I would doubt you would save any money this way, however.

In thinking about it, there are bearings in it that it can't hurt to have examined, the commutator surface and so on.

John

[bcomo]

That's good advice -- especially about the warranty, and being in town if I have a problem. That Generator is pretty heavy to mail back and forth if it has a problem after I get it re-installed.

I'll give them a call on Monday and see what they say.

Meanwhile, I'll take a voltage reading at the Arm terminal at the generator itself, and look at the end bell assembly.