weird electrical

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weird electrical

April 01, 2015, 03:25:53 pm

Just had the generator serviced and upon picking the coach up I noticed that my inside lighting was not working properly. Some of the lights didn't come on and some were dim. The monitor would show tank levels but not the rear camera. The propane detector would not come on properly at first (would just keep beeping as when you first turn it on). Then I noticed while driving that the alternator was not charging. As I had just left Cummins I had tested the genet and allowed it to run on my transit (after getting the propane detector to settle down). I discovered that if I loaded up the genet by putting on one of the A/C units, the alternator would start charging normally. Previous to this (over the last few months) I had noticed that occasionally the alternator would not be putting out and I'd shut off the engine and start it up again and then I'd see it working. I had the auto electric guy across from where I park the coach test the alternator for me and he said there was no 12v from ignition present (it is a Leece Neville) so I'm assuming that when the genet is loaded up I'm getting the necessary 12v which allows the alternator to work. Obviously with the genet running the 12v lighting came up but the back up monitor did not until I switched to shore power once backing in to the storage lot without it. Perhaps it would have had I allowed the genet more running time and this was just coincidental. I checked both batteries with the charger turned off and found my house battery below 12v. I'm perplexed as to why the alternator would not put out with the chassis battery above 12v and with enough umph to turn the starter. I understand that the house battery being bad would effect the 12v lighting and the monitor and even the propane alarm but why is it effecting the 12v from the ignition at the alternator? I've ordered a new 8D AGM house battery. I'm going to disconnect each battery one at a time and check for 12v at the alternator exciter stud with the wire from the ignition to see if something is cross wired or perhaps the isolator is bad. The house battery shouldn't in any way effect the 12v to the alternator...right? Anyone have any explanation. BTW, boost switch was off.

Re: weird electrical

Reply #1 – April 02, 2015, 09:00:38 am

Dwayne, Check the external exciter wire to the alternator. Without 12 volts the alternator will not work. Not familiar with your model but start at the alternator and trace the small wires back to their origin to see if there are corroded connectors or breaks.,
Gary B

Re: weird electrical

Reply #2 – April 08, 2015, 11:02:07 am

Installed the new battery but having the same problem except that 12v lights all came on normally and after several attempts was able to get the propane detector to stop chirping allowing me to fire the generator up. Tested the exciter wire and only getting 3-4 volts. Battery connections all look good but I'm going to clean them up (at isolator too) to see if that helps. The only way I see good strong voltage on the dash voltmeter is to run the generator with a load on it. I'm guessing I could have a bad isolator or ignition solenoid but that is just a WAG.

Re: weird electrical

Reply #3 – April 08, 2015, 11:13:11 am

Both ignition solenoid and battery isolator are easy to test.

Ignition solenoid: When you turn on the key, all things that work with ignition on work-- Allison shift pad illuminates, dash HVAC fan works, etc. It is under the drivers' side of the dash-- just raise the top of the dash to access. If not working, give it a sharp tap with the plastic end of a screwdriver for (very) temporary fix.

Battery isolator:

Center lug from alternator. Should read in the high 14's with engine running at high idle (like 1100 RPM). If not, check alternator, starting with verifying wiring, particularly the small sense wire from battery isolator to alternator.

Outer lugs go to batteries-- one to each battery bank. Should read in the range of 14.0- 14.2 with engine running at high idle.

Re: weird electrical

Reply #4 – April 08, 2015, 12:32:23 pm

Quote from: Dwayne – April 08, 2015, 11:02:07 am

Tested the exciter wire and only getting 3-4 volts.

Dwayne,

Check this wire connections along with the circuit breaker. We have had our circuit breaker go on the fritz and have had bad voltage, not steady but broken voltage resulting in erratic charging.

Pamela & Mike

Re: weird electrical

Reply #5 – April 08, 2015, 03:04:39 pm

Which circuit breaker are you referring to?

Re: weird electrical

Reply #6 – April 08, 2015, 05:35:53 pm

Dwayne,

On the U-240 we had the breaker was mounted next to the boost solenoid close to the battery isolator. One wire came from one of the cranking battery post and the other went to the alternator. It was a lot like our 320 is today. Here is what ours looks like http://www.delcity.net/images/photos/72302_primary.jpg

Pamela & Mike

Re: weird electrical

Reply #7 – April 08, 2015, 10:59:10 pm

That looks familiar. I'll check it. Prior to not charging at all the alternator would start charging if I shut the motor off and restarted it. This happened several times. Now it appears I'm not getting the requisite 12v at the exciter wire.

Re: weird electrical

Reply #8 – April 11, 2015, 12:35:00 am

Now there is 12v at the exciter wire so auto electric guy must have been mistaken. Still no charging so must be the alternator. Strange thing happened though, tried to start motor and nothing happened. Tried again with boost on. Still nothing. Turned headlights on to see if that worked. Tried again to crank her and she fired right up. I do have a gremlin and bad ground is usually the culprit.

Re: weird electrical

Reply #9 – April 11, 2015, 08:20:43 pm

Well, that breaker you pointed me to is exactly where you said and wired as you said. It was fried. I replaced it (couldn't see amps on case but inside the number 15 was printed at each corner. Auto parts places only had 20, 30 or 40 amps so I used the 20). It didn't fix my problem. I am registering nothing on any isolator post. I do have 12v on the two small center alternator posts but nothing on the bigger two. I'm wondering why I'm not seeing 12v on the isolator post that goes to the chassis battery to sense voltage for the alternator. how do I test isolator without any juice from the alternator? I don't think a bad isolator would prevent alternator from charging so long as I have 12v at the exciter. Next stop alternator shop.

Re: weird electrical

Reply #10 – April 11, 2015, 09:41:16 pm

Those two outer isolator lugs should (check the wire numbers) go directly to their respective batteries.

Said another way, they should always read battery voltage.

Re: weird electrical

Reply #11 – April 11, 2015, 10:59:26 pm

I confirmed with a test light voltage at both batteries, voltage at two small posts on alternator with key on and nothing on any isolator post. I'm not sure what to do now. The only place I know of around here with motorhome electrical system knowledge is Lazydays ($$$$$).

Re: weird electrical

Reply #12 – April 12, 2015, 02:20:44 am

Make sure your alternator has a good ground connection. To test alternator, remove it and find an old-timer alternator/starter repair shop. Be sure to identify to them about your two small terminals as to which is which.
Does a test light tell you the voltage reading? Maybe an inexpensive Harbor Freight volt meter is needed. What lights bulb may not excite the alternator.

Re: weird electrical

Reply #13 – April 12, 2015, 08:26:11 am

Dwayne,

Trace those large cables physically from isolator outer lugs to the batteries themselves.

Re: weird electrical

Reply #14 – April 13, 2015, 08:39:48 am

Cables look good from isolator back to battery bay. I did find that the ground in lower left corner of photo looked bad so I cleaned it up. I have good voltage everywhere along isolator except for the boost solenoid (if that is what it is) located next to the isolator. However, I know that when I push the boost switch I can see a reaction on the dash voltmeter and prior to replacing the house battery last week when trying to start generator I'd get more oomph with boost so I believe it is working. Perhaps this solenoid is not the boost...there is another solenoid just like it in the photo from the battery bay....can anyone tell me what this one is for? Alternator is now at the auto electric shop.

Re: weird electrical

Reply #15 – April 13, 2015, 09:15:29 am

Dwayne,

If the cables are good from batteries to isolator, the outer lugs of the battery isolator will be powered/supplied with battery voltage.

That is the point I am trying to make.

Re: weird electrical

Reply #16 – April 13, 2015, 10:36:51 am

Quote from: Dwayne – April 13, 2015, 08:39:48 am

Perhaps this solenoid is not the boost...there is another solenoid just like it in the photo from the battery bay....can anyone tell me what this one is for?

It is very difficult trying to diagnose electrical problems from a distance. It sounds like you may have multiple problems, which are not necessarily related. You must use a systematic approach to determine the faulty circuit or device. Do you have a wiring diagram for your coach? This is a essential tool for tracking down these problems. For instance, you have a "solenoid" which you cannot identify. Using the wiring diagram, it should be easy to determine the function of the solenoid. Testing a solenoid is simple: it should be always "HOT" on one of the large terminals. Apply 12V power to the small terminal, and then both big terminals should be hot. The big question is, what is the source of power suppling this solenoid, and where does the power go when the solenoid is "activated"? Without a wiring diagram, this can be difficult to determine.

On my coach, mounted on the battery isolator board, there are 2 solenoids (see photos below). The one on the right is the "BOOST" solenoid, and the other is the "AUX START" solenoid. They look physically identical. If you have located the "BOOST" solenoid on your coach, then the mystery solenoid may be the "AUX START" solenoid. Or it may be something else - once again, without a wiring diagram it is difficult to say.

Good luck tracking down your gremlins!

Re: weird electrical

Reply #17 – April 13, 2015, 11:29:44 am

Your U240 may be wired differently from my U280, but I am comparing your photo to my wiring diagram. In your photo, you can clearly see that one of the large solenoid terminals is connected directly to one of the 90A circuit breakers. On my coach, only the "BOOST" solenoid has any (electrical) connection to the 90A circuit breakers. Another clue: the "BOOST" solenoid has heavy gauge cables attached to both large terminals. The other solenoid has much lighter gauge wires connected to the large terminals.

I think the solenoid shown in your photo is the "BOOST" solenoid, and the other solenoid (wherever it is located) is the "AUX START" solenoid.

Re: weird electrical

Reply #18 – April 13, 2015, 02:17:29 pm

Thanks. Just got word that the voltage regulator on the alternator is bad. $48 repair so not bad. Now I have to fight that thing back in there and fight the belt back on. It was acting weird...charging then not but would start working again after shutting down the motor and starting it back up again (before crapping out completely). I'm guessing either the corrosion at the negative posts from my panel in the photo above or the bad house battery caused the failure. I think the alternator is charging both batteries at all times. That alternator didn't have 5000 miles on it. Perhaps Brett remembers where his boost solenoid was located on his 240. Mine is probably in the same spot.

Re: weird electrical

Reply #19 – April 13, 2015, 04:43:07 pm

Dwayne,

On the 1993 U240, the boost solenoid is on the front wall of the battery compartment (under the FG cover held on by two nuts). This is the basement compartment just in front of the passenger rear wheel where all the batteries are.

Have someone turn the boost switch on/off/on... You should easily hear it click as it engages/disengages.

The serpentine belt should not really be any problem to get off and back on. You have excellent access and all you need it the square drive (a ratchet) to detension it.

Re: weird electrical

Reply #20 – April 19, 2015, 04:59:02 pm

Thanks Brett, cofirmed boost solenoid is where you said. Alternator installed and working great. Belt wasn't bad at all. Still don't know what the solenoid next to the isolator is for. Voltage on one side only.

Re: weird electrical

Reply #21 – April 19, 2015, 05:46:29 pm

Quote from: Dwayne – April 19, 2015, 04:59:02 pm

Still don't know what the solenoid next to the isolator is for. Voltage on one side only.

Dwayne,

If you are talking about the one in the pic. it should be your start solenoid. When you turn your key to start it should close and supply closing power to the main solenoid on the starter. That is how our 240 was set up.

Pamela & Mike

Re: weird electrical

Reply #22 – April 21, 2015, 07:49:16 am

Quote from: Dwayne link=msg=193221 date=1429477142[quote author=Dwayne – April 19, 2015, 04:59:02 pm

Still don't know what the solenoid next to the isolator is for. Voltage on one side only.

That solenoid will also provide the pull power to the fuel shutoff solenoid when the ignition key is in the start position.

Roland

Re: weird electrical

Reply #23 – April 22, 2015, 04:21:39 pm

Thanks. All is well again with the rig. Selling is now on the back burner if not off the stove so time to start planning a little trip. I did loose my place to keep it with the shore power hooked up. Had to move it to my father in law's business where I have an extension cord to the converter/charger only so at least can keep the batteries maintained.

Re: weird electrical

Reply #24 – April 22, 2015, 04:25:31 pm

Glad to hear all is well.

Brett

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