Alternator problems

[DixieReb31]

Volts read 11.79 while engine not running. 
Volts read 11.73 while engine is running. Not getting a charge. This mill is only 8 months old (LT35HD).
Anyone else solve this problem?

[Southside]

Have you checked for a loose connection or broken wire? If the wiring is good the give WM a call. The regulator might have died in the alternator. It's under warranty. 

[DixieReb31]

Yes sir, I've checked all wiring harness and they appear ok, I'm afraid to do too much for fear of voiding the warranty. I do plan on calling WM tomorrow. Was just wondering if there was a quick fix or if someone knew a special trick. 

[barbender]

If they are still the same, my '97 uses a standard Delco alternator. When mine went down in the middle of a job I stole the alternator off my Chevy pickup and sawed on😊

[Percy]

Just a shot in the dark, but check the little wire connection plug on the alternator, the one that excites the windings, not the thicker one that goes to the battery. Mine gets a poor connection often...

[Southside]

If I need to replace an alternator these days I eliminate that style and just go with the single wire that self excites from RPM one less potential failure point is how I see it.  

[Ben Cut-wright]

Volts read 11.79 while engine not running.
Volts read 11.73 while engine is running. Not getting a charge. This mill is only 8 months old (LT35HD).
Anyone else solve this problem?

Are your voltage readings from a mounted instrument/meter or a DMM? 
Did you jump start the engine or did it start normally?
How long have you run the mill with this low voltage condition?
Are all the electrical devices operating normally?
Is the CHARGE LIGHT operating?
There are more questions than the few I asked because the "problem" isn't well defined as yet. 

[DixieReb31]

Are your voltage readings from a mounted instrument/meter or a DMM? Hand held volt meter
Did you jump start the engine or did it start normally? Machine sat idle for 2 months, motor was covered from weather. Had to jump it off when I started back. It has started up from then on. 
How long have you run the mill with this low voltage condition? Maybe 6 hrs.
Are all the electrical devices operating normally? Seems to be
Is the CHARGE LIGHT operating? Not sure I have one.
There are more questions than the few I asked because the "problem" isn't well defined as yet.

Side note: sometimes while engine is idling, (no blade engagement) it will just shut off.  Sounds like it's running out of gas and just peters out to all stop. But, it will crank right back up as if nothing was wrong. 

[mike_belben]

the charge indicator dummy light is also part of the field voltage supply.  if that bulb is dead the alternator cannot charge because the windings inside will not have any current to turn into a magnetic field.  consider it an alternator fuse.  thats not its purpose but if its blow it will behave like a fuse.  when you turn the key on the light should come on because one side has 12v and one side has zero.  once alternator is spinning the zero side comes up to 12 and no current flows so the light goes out.  if its dimly when running then theres a bit of current flowing which indicates either the alternator or the battery are getting low. an issue is brewing. 

if you have battery voltage going into the field wire and no magnetism around the center of the case then the alternator has a problem,  this is typically brushes used up or a big groove wore in the commutator but unlikely on a low hr unit.  if its putting out AC voltage your rectified bridge has failed.  if there is no voltage going to the field terminal you can apply it with a jumper lead careful not to get sucked into any belts, and see if it kicks up to full output. it should. 

sidenote- 1 wire alternators arent really that good at their job, fwiw.  they are simple and are fine for low draw applications like just starting and ignition spark.  high power drawing stuff you want load sensing and field wires so that the battery is never the source of power, the alternator is.  a load sense wire allows a much faster response from the alternator so that the battery is never doing the lifting and being drawn down because the alternator is putting more snot into it every time i click the winch or flip on the ambalamps lights or whatever.   really id suggest an external regulator too on something like a bargemonkey machine that has the lights on 16 hours a night. sorta on topic right?

[Ben Cut-wright]

OK, now you have provided some info we can sink our teeth into.  Some comments and more questions, as promised. ;D

Where did you take the voltage measurements? 

Since you only jumped started the "no crank battery", AND operated the engine for "six hours" after taking the reading of a (11.7 volt=25% charged battery), electrical accessories "seem to be operating normally", and the engine "starts right back up" after dying, the charging system almost has to be working to some extent. 

Does the engine die when operating the hydraulics or other electrical loads? 

Your owners/operators manual will specify as to the charge indicator light. There are other methods of excitation for the alternator but the charge light is the norm. 

[Southside]

There is no charge or alternator dummy light on an LT35, not even a gauge.  One thing you can do is kick the setworks off and then on again, it draws a heavy load on the alternator when starting up and you can hear the engine governor kick in as a result.  

[Ben Cut-wright]

There is no charge or alternator dummy light on an LT35, not even a gauge.  One thing you can do is kick the setworks off and then on again, it draws a heavy load on the alternator when starting up and you can hear the engine governor kick in as a result.  

Is amperage load greater when "kick the setworks off and then on again" or when operating the log lift or other hydraulic component?  The OP states "all electrical devices seem to operate properly".

I read your comment above as stating there is no provision, other than electrical faults or malfunction, to indicate a low-no charge condition on the  LT35?

[Southside]

Correct, there is nothing that indicates an alternator issue on the 35.  

[Al_Smith]

Just a general statement on alternators .In my thinking a GM one wire is the most easily adaptable bullet proof made today .I have them on two Ferguson tractors, one Jeep CJ5 .an Oliver OC 6 dozer .They can be found in the $65 range brand new .Most you can change the drive pulley rather easily to fit the application .The mounting however you need to have some mechanical ability though .I gave up on rebuilding them years ago because of the work involved it's much simpler to just find a new one .
If you don't have a working knowledge of automotive electrical systems there is plenty of help on the internet . 

[Ben Cut-wright]

Also  only making general statements regarding function of (self-excitation one-wire alternators) compared to three wire alternators. 


Self exciting alternators monitor the voltage and amperage demands placed on the alternator.  The three wire alternator uses a sense wire and is capable of monitoring the demands of the entire circuit and battery loads. Would seem a slight difference but it does provide more appropriate and constant voltage over the entire wiring circuits.


The excitation circuit provides for an idiot light which gives a visual warning of charging fault.  Normally, this also creates a more rapid magnetic field to build and charging is begun sooner than self-exciting units. Alternators driven at slower idling speeds can begin charging without the need of high RPM's.


It is a serious deficit for a sawmill, or any unit requiring a charging system,  NOT to have some method to warn of low or no charging.  

[Al_Smith]

You can hook up a one wire just like any other charging system by using an amp meter .However saying that I have no idea how this mill is wired as some designers have a tendency to use complicated electronic systems to monitor things that are relatively  simple .
Now repairing a malfunctioning alternator is another subject .First of all is getting the dang thing apart to work on it .An epic battle most of the time .Then determining if it's worn brushes ,a faulty diode trio or whatever .Could have worn bearings .The time and money these days they aren't worth tinkering with .
Might sound hard to believe but I used a big reostat for an external regulated  Ford unit  on a '57 Ford F-600  when I was too poor to even  pay attention and it worked instead of a regulator .Some times you have to do things a little bit half-fast ( say that real quick ) just to get by .

[DixieReb31]

Update:
Called WM and talked to their Tech. He walked me through several tests. His conclusion was a bad key switch and bad alternator. I had new ones before the end of the week. Replaced the old with the new. However, problem still persists. Battery is barely getting a charge. I placed a volt meter on the machine so I could watch as I used. Battery is using volts faster than alternator is replenishing. Tried calling WM again, but Tech was off that day.  So, back to where I was. Bumfuzzled.

[mike_belben]

if alternator is charging and battery is not then you have an open circuit in the connection from alt to battery.  If alt is not charging you still have an alt issue.  

While running above idle hold a magnet to the back center of the case without arcing anything.  Do we have magnetism?  13ish volts when measured from the alt chassis to charge lug?

If yes alt is good.  If not put battery voltage to the field terminal by jumper. Do we get magnetism? If no, alt dead or ungrounded.

If yes, check continuity of battery neg to alt case.  Should beep. If not, fix ground path.

Check continuity from alt charge lug to batt + terminal. Beep = go. No beep = fix charge wire.  

Alt should put out 13.x volts at the lug.


These arent external voltage regulators are they?

[Ben Cut-wright]

Update:
Called WM and talked to their Tech. He walked me through several tests. His conclusion was a bad key switch and bad alternator. I had new ones before the end of the week. Replaced the old with the new. However, problem still persists. Battery is barely getting a charge. I placed a volt meter on the machine so I could watch as I used. Battery is using volts faster than alternator is replenishing. Tried calling WM again, but Tech was off that day.  So, back to where I was. Bumfuzzled.

What tests were done to determine a "bad key switch and a  bad alternator"? Obviously the tests were not accurate, the new components are faulty, or there is/has been other problems all along.
 
Does the alternator test at charging level voltage AT the alternator (BATT terminal stud on alternator) when running?
 
What voltage are you using to determine "battery is barely getting a charge"?

Where did you "place a volt meter"?

Testing at one point in the circuit doesn't always indicate the voltage all around the circuit.  Battery voltage through a viable conductor must be available to the alternator in order to begin charging.  Alternator voltage must be available to the battery in order to recharge the battery.  Your volt meter tests must include results at sources, connections, and terminations to be informative.  The Tech you spoke with must have been fairly confident to ship new components as a result of your test results.  This means little if the battery is still not being charged properly, though. The ground circuit is just as important as the positive circuit and is tested in much the same manner.  "Volt drop" tests can detect faulty connections and poor continuity if done correctly. A test light is also a valuable tool when troubleshooting wiring.   

[doc henderson]

If the batt. gets low on voltage (sounds like that is not a problem) then if the alt is charging it should go up when running.  you can then try putting the batt. on a charger, or take to to be tested.  still have to find if it is the alternator.  what are the chances of getting a bad alternator out of the box, and or a bad key switch?  not impossible, but unlikely.  at least now you have spares.  a bad connection comes to mind, and the ground is quite a common problem on outdoor 12 V equipment.  good luck, and let us know what you find.  I once got quite upset with a Walmart tech who told me my batt was fine.  I was sure it was not.  I found a TSC batt +lead, that came loos inside the lead clamp.  I found as I was trying to find the problem as the sun was going sown and heard, smelled and saw an arc when I moved the wire.  I tugged on it and it pulled out of the lead lug, and was covered with corrosion.  it looked new on the outside.

[Jim_Rogers]

When I had problems the tech at WM told me to take a voltage check at the alternator first. Then work my way to the battery checking at each connection. If there was a more than point 2 voltage drop then that connection needed cleaning or repairing.

Jim Rogers

[Stephen1]

Here is my 2 cents. Simple version. The battery was dead from sitting for 2 months, probably on the contact strip. A dead battery will not charge on the WM when you are running and using hydraulics. The Alternators are not strong enough. It might have enought juice to start the mill but all sorts of troubles stem from a bad battery.
I would replace the battery with a fully charged battery and start testing from the ALT to the battery. 

[Al_Smith]

I'll see your 2 cents and raise it two cents .As general rule the lower the voltage the more problems arise from loose terminals .corrosion etc .12 volts is low you know plus a saw mill usually sets outside in the weather which doesn't help .The more modern use of push on style "quick connect " type of terminals just escalates the problems .I've already needed to cut them off and replace them with new ones just to correct a problem .It can drive you bonkers  chasing down "automotive " type wiring problems .Might take 3 days to find it then only ten minutes to fix it .

[Ben Cut-wright]

The WoodMizer tech help has always been pretty good, but....they can only go on what they are told when diagnosing remotely.  If the ground lead, for example, of the test instrument isn't connected properly, or the chosen ground is faulty, the test result is no good.  Keeping this in mind, "voltage drop testing" is a better method of testing connections. There are two methods of volt drop testing, one insures the connection test result is good or bad, and the other might NOT prove the connection or circuit sound, dependent on lead contact and circuit integrity. Also, a circuit could very easily pass a voltage test but be unable to pass a "load test".


It is most likely the case the WoodMizer tech help used test results given to them as basis for replacing the switch and the alternator.  Nevertheless, the alternator can be removed and taken to almost any automotive parts house and dynamically tested.  The key switch tests are not complicated.  IF, the probes of the test instrument were used properly there must have been some fault detected. No matter, all functions of the key switch are easily tested and verified as (good or fail). 


This is a fairly new machine ("8 months old"), surely passed basic tests when it left the factory.  This particular type of charging system is NOT hard to diagnose.  That does NOT mean all faults are easily found however.  There is info at the woodmizer site and others regarding charging system testing.  Components can be tested individually and as a group.  Parts have been replaced but no info has been provided as to what tests proved these parts were defective. 

[mike_belben]

Battery could be completely junk.. If it just barely starts the machine the alt should kick out high 12V minimum then eventually get into the 13s.  Theres plenty of juice in an 11V battery to excite the field and bump out some amps. 

[Ben Cut-wright]

The combined problems the OP expressed are quite often topics of forum posts.  Engine dying, dead batteries, poor performance of electrical accessories, all these I find interesting faults and try to keep up with whatever resolve they illicit. Others have added voltmeters and ammeters and suggest different alternator styles.  Why this model sawmill does NOT include a gauge or light to warn of no or low charging is a mystery to me. No matter how new or recently replaced a part or unit is it can have faults.  All this makes it difficult  to diagnose and to help others when a problem occurs. WoodMizer phone help is excellent. Their assistance in getting a machine back working properly is UN-excelled IMO.  There are but a few tests needed to ascertain a direction for further testing or repairs.  All these tests require an accurate test point and an understanding of each test result with the test tool used.  At any point in the diagnosis there comes opportunity for errors that have no or little meaning in the actual fault solution. Where to begin the diagnosis and what steps to take will be dictated by the health of the complete circuit and its components.  What is working is as important as what is NOT working.  How well something is working is often too subjective to be used by someone not present. Example, if the starter is able  to rotate the engine it does not mean the battery and starter are sound. 


Posts often state the engine dies when an electrical load is placed on the charging system.  Does this mean the electrical supply is diminished or the actual engine load on the charging device was too great?  Either way the engine dies.  Of course there are many, many other reasons an engine may cease to run not confined to charging or battery health.  This is what I mean by tests that can quickly confirm a direction for further testing. If the electrical supply tests sound when the dying occurs, something else is causing the engine to die. 


In this thread there are more possible faults.  Begin with the dead battery, or too low a battery to start the engine.  Was the battery merely jumped or was it charged to some extent. The OP says the battery operated the electrical accessories for a lengthy period after getting the engine started.  A battery may not charge even though the charging system is trying to recharge it.  That is easily tested. If the charging device is charging/not charging then you have direction for further testing. The manufacturer sent new components and the problem persists.  We have no test results indicating why the alternator and ignition switch were replaced or if any other testing of the circuits for these components proved good or faulty. It would be mostly guesswork or speculation past this point.


I do hope the OP has resolved his issue and presents us with the cause and results of what it took to get there.

[DixieReb31]

WM LT 35 HD. Less than a year old.  25 hp gas. 
Problem: Hydraulics are using battery juice faster than the alternator can recharge. OR the alternator isn't charging the battery quickly enough. I put a volt meter on to watch the charging.  I think the alternator (brand new alternator sent to me from WM along with a new key switch) isn't charging as fast as it should.  Cannot figure out why.  I can cut about 3 logs before the machine just shuts down from low amperage.  I replace the battery with another deep cycle marine battery and I can saw more while the first is on charge.  But swapping batteries every 2-4 logs gets old quick.

Question: can the hydraulic pump be converted to AC? That way I can bypass the alternator.

[Ianab]

I'd be looking at all the Earthing connections in the circuit. If you have a bad connection there it adds resistance to the charging loop, and that creates a voltage drop. What you might then find is the alternator produces it's 13.8 volts on it's terminals, and you have 13.8 (to ground) at the battery +. But you may only find 13.3 across the actual battery terminals (not enough to charge properly). The missing 0.5 volts is warming up an earth lug someplace. An accurate voltmeter directly across the battery terminals would give a clue here. Especially if it's different from the voltage being produced at the alternator. 

It does seem you have eliminated the obvious causes,. so it's now on to the less obvious ones. 

I imagine you could swap the pumps for electric ones off a stationary all electric mill, but that seem a bit excessive as they wont be cheap. 

[Magicman]

My alternator supplies 14.5+ volts and easily keeps my battery charged.  Voltage is what charges the battery.  As Ian suggested, read the voltage at the alternator and at the battery.  The reading should be virtually the same.  If they are not, then move the voltmeter leads to various check points within the circuit to identify the bad/loose connection.

[mike_belben]

Check for continuity from the alt case to the battery ground post. Should be almost zero ohms, and should beep a meter.

Check if the alt case itself has any voltage with a meter.  Black lead to battery negative post. red lead to alternator case.  It should read zero volts.  

Run the machine, record alternator charge post output.  It should be in the 13s.

Now briefly put a jumper wire from battery positive post to the alternator field terminal.  This will create full output. Should be into the 14 volt range with strong magnetism on the case. 

If there is a dummy light bulb it MUST work. Dead alt warning bulb means no field voltage. With key on engine off tge bulb should light then go out when running. 

[DixieReb31]

Thank you Mike, I will try it this evening when I get home.  I'll let you know what I find out.

Electrical issues seem to be my Achilles heel.  

[SawyerTed]

This is one of those overlooked but simple items that shows up as other problems.  It will cost 0 money to eliminate this as a possible problem.

If you haven't checked the contact shoe for the hydraulics that rides on the bottom of the rail, check it to make sure it is making contact.  It is held in contact with springs and can get bumped out of contact.  I experienced similar problems and I started with a battery replacement.  While replacing the battery, I saw the contact wasn't right.  I adjusted it, put the old battery back in and no more issues.

In the manual or on the website look at the drawings for the Hydraulic Power Supply Strip.  It will show parts 14-24 for the ground contact assembly.  

[mike_belben]

Good to know ted. 

Thats the kinda machine specific info that ya really need, which i cant be any help with having never had my hands on half the stuff we are on here trying to troubleshoot. 

Let us know what ya find. The more details the easier it makes it for others to help ya find the issue.

[Ianab]

Yeah, that's another connection in the charging loop that needs to be checked. And being a moving one, it's more likely to give problems. 

[Ben Cut-wright]

WM LT 35 HD. Less than a year old.  25 hp gas.
Problem: Hydraulics are using battery juice faster than the alternator can recharge. OR the alternator isn't charging the battery quickly enough. I put a volt meter on to watch the charging.  I think the alternator (brand new alternator sent to me from WM along with a new key switch) isn't charging as fast as it should.  Cannot figure out why.  I can cut about 3 logs before the machine just shuts down from low amperage.  I replace the battery with another deep cycle marine battery and I can saw more while the first is on charge.  But swapping batteries every 2-4 logs gets old quick.

Question: can the hydraulic pump be converted to AC? That way I can bypass the alternator.

Describing the results you see does not define the *problem.  You present TWO scenarios that could contribute to dead batteries and cause an engine to die.  "put a voltmeter on to watch the charging" has NO information we can use.  How many volts are you reading at the alternator and at the battery when the hydraulics are not in use?  What are the readings when the hydraulics are in operation?  Volts alone will NOT tell the entire story.  Volts are pressure but amps are volume.
 
The assumption the "battery isn't charging fast enough" encompasses to many variables to conclude anything.  Battery state of charge, alternator voltage and amperage, and electrical demands all have to be accounted for to conclude such a thing.  It is possible to eliminate many faults and test for proper operation to determine where the fault resides with simple tools and step by step testing methods.  A test light will clearly and accurately show voltage drops across poor connections. A voltmeter will certainly indicate healthy voltages and can be used to test more accurately for voltage drops. 


No idea how the hydraulic contacts could cause a dead battery or dying engine though.  An Achilles heel in electrical will make converting the hydraulics to AC very difficult.  The unit as designed will/should preform more than adequately for the task.    

[Jim_Rogers]

Many years ago, when I had an issue with the engine dying when I ran my hydraulics the tech guy at WM told me it was my battery.
So, I replaced it.
Another time when I had issues with the alternator not keeping the good battery up, he told me to check the voltage at the alternator and note the amount. Like write it down.
Next, he told me to go to the next connection in the circuit from the alternator to the battery and check the voltage there. He said if there was a voltage drop of more the point 2 volts then that connection had an issue. Clean it and or repair it so that there is no voltage drop. Continue this process until you reach the battery.
I believe it was mentioned above that the red light on your dash, if you have one, needs to be working in order for the alternator to charge the battery.
Good luck with your search and repairs.
Jim Rogers

[stavebuyer]

Bypassing the DC hydraulics was the best upgrade I ever did. The factory hydraulic system has a multitude of pitfalls and limitations. 

[stavebuyer]

Here are some links showing Bibbymans hydraulic upgrade project which I later copied and adapted for my LT70DCS. There is a really detailed thread from his original build some where but I haven't found it yet.

Any mods for faster hydraulics of portable woodmizer in Sawmills and Milling

Plumbing an LT-40 to a stationary hydrualic power pack. in Sawmills and Milling

[DixieReb31]

Test results

Test 1 - Continuity
Red lead to + on Alt. Black lead to - on battery - results = nothing happened. Meter screen made no movement and did not beep. Meter was set to continuity correctly. 

Test 2 - Voltage (engine not running)
Black lead to - on battery. Red lead to + on Alt. Results = 12.24 v

Test 3 - Voltage (engine running)
Same set up as prior test - 
Result = 12.11 v

Test 4 - jumper wire (not sure I did this correctly, not sure what you meant by "Alternator FIELD terminal). 
I assumed you meant the yellow wire that excites the alt.  This is what I did. Black lead to unplugged yellow wire.  Red to + on battery. Results = 12.03

I hope this helps. I do appreciate the input. 

[Magicman]

All of your voltage readings are too low.  A fully charged battery should read at least 12.7 volts and your alternator should be putting out close to or above 14 volts.

Neither the hydraulic contact strip nor the ground on the bottom of the rail have anything to do with your alternator charging the battery.

[DixieReb31]

I don't disagree.  Any idea as to why they are too low?  I have traced all the connections and they are clean and tight. 

[Magicman]

No, I can't personally help you without being there, but obviously your alternator is not supplying enough voltage and your attempted usage has drained the battery down. 

Your alternator has to put out first.

[doc henderson]

if the voltage does not go up when running, it must be the alternator, or voltage regulator if it has one.  

[Jim_Rogers]

Does the red light lite up when you turn the key on? and not start the engine. if not then it is burn out. and alternator will not produce juice.

Jim Rogers

[Ben Cut-wright]

Test results

Test 1 - Continuity
Red lead to + on Alt. Black lead to - on battery - results = nothing happened. Meter screen made no movement and did not beep. Meter was set to continuity correctly.

Test 2 - Voltage (engine not running)
Black lead to - on battery. Red lead to + on Alt. Results = 12.24 v

Test 3 - Voltage (engine running)
Same set up as prior test -
Result = 12.11 v

Test 4 - jumper wire (not sure I did this correctly, not sure what you meant by "Alternator FIELD terminal).
I assumed you meant the yellow wire that excites the alt.  This is what I did. Black lead to unplugged yellow wire.  Red to + on battery. Results = 12.03

I hope this helps. I do appreciate the input.

(Test 1) What, exactly.... did the meter *setting position have written beside that setting?   Your leads were placed to read VOLTAGE.  The test device might not be working now or accuracy may be shot.

 
IF, if...the meter is correct in (Test 2 and 3) you have NO battery charging.  Probably no alternator charging either but your tests cannot reveal that the way you had the leads connected.

 
(Test 4) has no useful information.

 
Continuity is a test using proper tools and methods to qualify the BASE integrity of a wire or circuit.  Think of continuity testing in that it proves ONE wire or connection or switch is capable (or not) carrying electricity.  It's NOT a load test, only that a circuit is available.  Normally a very low voltage is placed across the tester leads and then OHMS are read at the setting selected.  This test does NOT insure the circuit can operate properly.

 
It would be advisable for you to follow testing procedures precisely as advised using a simple test light and multimeter.  The test light can provide a quick indication of voltage and ground and is useful in testing voltage drops and opens at connections.  You need to test starting at the start, the beginning of the circuit, and confirm each connection and device is operating properly.

 
Step ONE should be to confirm the alternator is wired correctly,  voltage and grounds are sound and proper, and the signal to begin charging is present with key on.  Best I can tell, this has not been confirmed.  Pretty basic steps and pretty easy to explain, IF each step is followed exactly and each result is accurate and understood.   Lets say your Test 2 was correct.  That means the wire to and from the alternator and battery has continuity, but does not prove it is adequate to carry load.  Test 3 then, would indicate the alternator was NOT charging.  That dictates that the excitation circuit needs to be tested.  Plenty of members here who affirm there is NO charge light on these models, the LT25's.  A charge light indicator uses the resistance in the bulb  filament to place a small load on the excitation circuit and thereby create magnetism to begin the charging.  Some alternator systems, delco among them, utilize a voltage with no resistance to switch the regulator.  In either case the signal wire can be disconnected and the signal can be tested. Key off, no voltage. Key on, voltage present at the disconnected wire.


These are basic tests and as such might entail a variance during testing steps.  There is NO benefit in testing other points if the circuit isn't proven sound from the beginning.  You must use correct settings on your test device. You must have the clips affixed soundly to the test points.  The test points must be the correct ones for the tests to be taken.  Don't waste your time testing anything if you aren't sure what to expect and how to do it.  This isn't the place to experiment.  If expected results are not achieved, double check what you did before replacing or repairing.  Honest, this isn't that hard.

[Jim_Rogers]

Sorry, I didn't know this model didn't have a red light.
I'll back out now, and not offer any incorrect advice.
Jim Rogers

[mike_belben]

Test one you misplaced the positive lead We need to know that the alternator CASE has a path to ground, it should not have continuity the way you tested, from the charge lug to negative.  It should have continuity from charge lug to battery positive post. 



So far its sounding like a bad alt. I dont remember if youve replaced it or not.  No idea what alt you have or what wires go to what.  Any alternator needs voltage to excite the field windings and make magnetism.  Youve got none.  

[biggkidd]

This is probably to simple to be possible but have you made sure the alternator belt is tight and not slipping? My daughters truck kept having a dead battery because her belt was slipping enough to keep it from charging well. Amazingly not all slipping belts make noise. New mill new belt might have stretched a little during break-in.

[Ben Cut-wright]

@biggkidd:

Interesting thought, but it is hard to imagine a loose belt is the problem since he has replaced the alternator.  Surely he would have noticed a loose belt on the original unit and certainly must have know to tighten the belt when he installed the new one. 

[bannerd]

You'll need a multi-meter... you'll need to contact the positive post on the alternator and then ground it.  Typically found by itself off set to the housing.  The alternator needs to be reading around 14v.  Anything lower than that and you're out of load range and your battery will never fully charge or become retarded from the incorrect load.  If it's the IGN/IND switch you can test that fairly easy, a fault would degauss the magnetic current to the circuit.  A flat blade screw driver to the back of the alternator on the center cap/split ring location will stick to a working alternator because of the magnetic field.  

If it is not present or engaged cross the two wires where plug is and test the magnetic field again.  Sometimes this will not engage until an certain rpm is met which gives the rectifier a certain level of charging capacity to excite it.  If this is a self energizing alternator then you most likely will not have the above, just a single wire out feed.  Isolate the alternator by removing the positive wire and the ign/ind plug.  If that is outputting 14v AT the alternator then you know it's not that and move to the next problem.