I am reaching out for some trouble shooting assistance on my nonfunctional alternator. I am at the end of my patience.
Long story short - my alternator quit charging several weeks ago. I took it into a local rebuilder and had it completely rebuilt. Rebuilder was supposed to replace all wear parts, bead blast housing, and make my original alternator "like new". Waited four weeks for a one week turn around promise. I was very disappointed when my "price no object" rebuilder handed me back my alternator with a spray can painted silver over grease "rebuild". Figured I would hold my frustration and just be content with a functioning (but not too pretty) alternator. Took it home, installed it, and grrrrrrr - nothing. No output.
OK - not going back to that rebuilder (although I probably should have). Took it to a different rebuilder, new bearings, stater, rotor, voltage regulator, bead blasted housing, completely rebuilt and beautifully done. Now I am excited to get it home, installed, and my GV back on the road. Installed tonight and GRRRRRRRRRR - no output again.
Now that I am finished venting - what am I missing? GV is completely original and nothing has been buggered or changed. Batteries are charged, I have 12+ volts at the sense wire post on the alternator to the isolator. I have no voltage to the ignition terminal on the alternator key off - or key on.
Question: is there a relay or fuse in the ignition switch to alternator ignition terminal wire that could be the issue? I assume there is a wire from the ignition solenoid under the dash all the way back to the alternator - but am at a loss. Could it also be that the voltage regulator is wired incorrectly inside? No other problems, engine starts fine - just no charging from alternator
Any assistance would be appreciated - I would actually like to drive my GV this summer.
Others will chime in here but sounds to me that they did not make it for remote sensing. This is a different set up than the normal way so take it back and tell them to set the wiring that way.
JohnH
Did you try applying 12 volt to the IGN terminal with a jumper wire? If that "excites" the alternator into putting out, then at least you know it works.
I was sure tempted to - but was unsure that I could jumper it without burning something up inside.
It seems reasonable to jumper the 12 volts - so I will go out and give it a try.
thanks - will report back
The ignition wire should read 12v with key on. There should be a fuse in the fuse block labeled "alt exc" on your schematic. My fuse is a 10 amp. If your alternator had a short before the rebuild, it could have blown the fuse. The suggestion to try a temporary excite wire will help troubleshooting the problem.
If the alternator works (with IGN terminal jumper wire), then all you need is a "hot with ignition switch on" source in the engine compartment. If you have a remote start panel, that is the best source. Might also be able to use the Hobbs meter, but not sure about that. Seems like there is also a "hot with ignition" source on the isolator panel - can't recall for sure.
My alternator is "self-exciting" so I don't need the IGN wire - otherwise I could probably be more helpful.
OK - just tried the jumper wire and BINGO!
13.8 to 14.2 volts
funny thing is - with the engine running, I can remove the jumper wire and the alternator continues to charge.
Once I shut off the engine and restart - no output,
then I can re-jumper & away it goes 13.8 volts
SO - alternator is in working order. I just need to figure out where I am missing the 12 volts from the ignition wire to the alternator.
locations????? I will try and locate that fuse
That's the way the "Excite" function works - all it does is "wake up" the alternator and tell it to get to work. After that, not needed until next time.
COOL. Glad that worked. Reduces a big headache to a minor pain.
If there is a fuse or relay in the wiring from the ignition switch solenoid to the ignition post on the alternator - I will be darned if I can find it.
There is a 12 volt fuse panel under my dashboard and another 12 volt fuse panel in the back bedroom bed pedestal.
Near as I can tell - all fuses are functional and none labeled alt exc
anyone with more info?
I know in my case the regulator was replaced with a different one and caused a drain on the battery. Hehr was swapped with leece I believe and created a problem, so had to go back to original.
When Peter mentioned the "alt exc" fuse, I looked on my wiring diagram and could not find it. My diagram does not even show a IGN wire going to the alternator - only a SENSE wire. I guess my coach was equipped from the factory with a 3-wire, "self-exciting" alternator. Since our coach is a '93, I thought (hoped) the '91 models might be different. Wonder why he has the fuse and you do not? He has a DD, you have Cat, I have Cummins. Sometimes there are differences in wiring due to differing engines.
You either need to determine the origin for your existing IGN wire and why it is "dead", OR, locate another wire that is hot with ignition.
How about the remote (engine compartment) start panel? Do you have one on your coach? I know members in the past have tapped that panel for the IGN source to activate alternator.
Or the Hobbs meter. The Hobbs hour meter (on my coach) gets it's ground path through a oil pressure switch, so it doesn't start counting until the engine starts. However, the meter positive terminal should be hot when ignition switch is on (but I haven't actually verified that premise).
Another solution. Scott (RRadio) tapped into the wire going to the heater on his air dryer:
rewiring Leece Neville alternator properly (http://www.foreforums.com/index.php?topic=18363.msg125676#msg125676)
I do not know if this is your problem, but when I had mine rebuilt I had to make sure that it came out of the shop as a 4 wire set-up not 3 wire as they wanted to make me think it would work. here is my old post;
Update ! ^.^d I returned to the shop with my Hehr alternator that had a new Leech Neville Regulator installed. I also took along a conversion diagram that I found in "Beam Alarm Site" for converting a three (3) pole regulator to a four (4) pole regulator. The shop did the modification at no charge, I installed the old re-built alternator, with the New Leech Neville Regulator, that had been modified to allow for a voltage sensing wire (Red) from my remote start panel (an existing wire) . The system now works better than it ever did. Charging at 14.1 volts when at idle, the alternator had never produced more the 13 volts, and at idle would drop below 12 volts... I am a Happy Camper ;D ;D ;D Here is the link; Modifying 3 wire Alternator to a Foretravel 4 wire
I will post a picture in AM of the new set-up
Thanks to everyone!
The original alt. on our 91 GV was a 105 amp Leece Neville. I replaced the regulator in it a couple of times and finally just replaced the alt. with a Leece Neville 160 amp alt. It is self excited and only has one wire for sensing on line voltage. It charges most of the time around 14.1 volts at idle, but that also depends on how heavily loaded it is. The 160 amp capacity makes a big difference in output when I run cross connected while traveling. The 160 amp alt. is the same as the 105 amp one and just goes back in mechanically and electrically the same. The 160 amp one is a model 8LHA2070VF. Have a great day ---- Fritz
The forth wire is not an "excite" wire it is a "Sense" wire. That must "Sense" 12 Volts from the ignition for the alternator to work. ^.^d This post had to be added to my rebuilt alternators' voltage regulator for it to work. They also told me originally that it was "self exciting" and did not need the extra wire, however on Our motorhomes that have an "Isolator" the "Sense" wire is necessary. ???
Gerry,
Perhaps some terminology issues. With a 4 terminal alternator:
B+ to center lug of battery isolator
Ground-- to solid chassis ground or battery negative
Sense wire-- to chassis battery side of battery isolator (can be to any connection as long as it is "past the isolator").
IGN-- a wire that is 12 VDC positive only with the ignition on.
Sounds like his alternator is fine, he just needs to find why the ignition wire to the alternator is not getting voltage with the key on
My alternator has only the sense wire and no "ignition on" wire. If I've said this once I've said it 3 times, if your alternator (rebuild) was NOT internally modified for DUVAC system, it will not work. I fought with mine for a year before I was finally educated.
a picture is worth a thousand words.
1. new voltage regulator - exact same model number as was on my pre rebuild
2. far left larger wire - black chassis ground
3. next - small terminal with a wire coming from somewhere inside the voltage regulator. this is supposed to be the "excite" terminal. Currently NO 12 volts with ignition on or off. There is actually no external wire connected to it (and wasn't before) so how it is supposed to get 12 volts from the ignition switch when ignition is on is a complete mystery to me. Nothing on my wiring diagram either. I just know it used to work when wired this way. Thanks to forum members - I can jump 12 volts directly to the terminal and the alternator works fine.
4. heading to the right - next small terminal with small red wire. "sense wire" to battery isolator - chassis battery side of isolator. constant 12 volts.
5. Far right larger wire - 12 volt output from alternator to center post of battery isolator (charges house & chassis batteries).
My guess is that something inside the voltage regulator and landed to the excite terminal is wrong. Still wanting to understand how 12 volts from ignition switch could possibly power the excite terminal - since there is no obvious direct wiring path. In the meantime - I can jumper 12 volts to the excite terminal from my fuel shutoff solenoid and drive my GV. Please - keep the brainstorming coming in. I would like to fix it "right"
So you never had a IGN wire attached to your alternator? That puts a entirely different spin on your problem. Your initial post made it sound (to me) like there is a IGN wire connected to alternator, but it is not "working". Now it is clear there never was a external IGN wire!
So now it appears that your alternator was either designed to be "self-exciting", or was modified to work in that way. The 12 volt signal on the small IGN terminal has to come from inside the voltage regulator. That is probably the function of that little dark colored jumper wire. If this is not happening, then it would appear that Twig (post above) is correct, and the last rebuild was done improperly.
What is the model number of your alternator? There should be some online wiring diagrams for that model, which would show the correct hookup for both "excite from external IGN wire" and "self-excite".
Ok. That is exactly the same as mine. That small wire (excite) that comes off the regulator runs back to the start battery lug on the isolator through an automatic reset fuse attached below and near the isolator. That red wire is ALWAYS hot. If you don't have 12 V there all the time it won't work. Follow the small red wire from the isolator towards the alternator and you should find the 1"x1" fuse along the way. It is a small black box. This could be your entire problem. I had to replace mine.
Edit: IF your rebuild was correctly done, once this excite wire has 12V continuously it will work. IF it has not been modified for DUVAC (not properly rebuilt) then your start battery will go dead overnight even with nothing on.
Crownbus (would be nice if we knew your name),
Here is a simple explanation of how "self excite" works in a (Delco) alternator. The principle should be similar in your Leece-Neville. You can see that it does not require any kind of wiring or communication between the ignition switch and the alternator. The voltage that excites (wakes up) the unit is totally generated internally. I believe this is what the rebuilder attempted to accomplish on your unit, but he didn't get it right. It also touches on the function of the two small posts, and what wires should be connected to them.
What is a self exciting (one-wire)alternator? How to solve Alternator Wiring... (https://alternatorparts.com/what-is-a-self-exciting-alternator.html)
I believe you meant to say "That small wire (sense) that comes off the regulator..." We don't want to confuse this issue any further. 8)
To paraphrase (part of) Brett's comment (above):
Sense wire -- to chassis battery side of battery isolator (can be to any connection as long as it is "past the isolator").
Excite wire (IGN) -- a wire that is 12 VDC positive only with the ignition on.