***Need help!*** Things are not going well.

[Barn Owl]

We are leaving on vacation in a week and I took the bus on a one night shake-down and everything went great. I got home and was working on some odds and ends, restarted the bus, and now the generator light will not go out. I am at a loss to where even to start. Does anyone have an idea how to troubleshoot this? My anxiety level has just hit an all-time high.

Thanks in advance.

[Barn Owl]

I am reading the maintenance manual. I am hoping for further light and knowledge from my bus-nut friends.

[Sammy]

I have never wrenched on your model bus, but have done many,many others. Having let you know this in advance, here's some suggestions:
1.Check the condition of your batterys - isolate them from each other, check voltage on each one. If they are in a low state of charge, charge each one individually. Re-check voltage on each battery.
Load test them if possible to confirm condition of each one.
2. Now that you have verified proper battery voltage, and cleaned and secured all battery connections,locate your voltage regulator.There should be a BAT or POS terminal on it. You need to verify if there is voltage at this terminal.
3.Your coach probably has some type of generator relay, might even have a low air cut out switch too.
Low air switch usually interrupts signal voltage to gen relay, gen relay controls voltage supply to regulator.
These are 2 more things to identify and test on your coach - if you have them.
Send me a schematic if you have one, I'll help you troubleshoot it further and make the repair.
Hope this may help you a bit. Good luck.
Sammy 

[jjrbus]

 Do you also have a voltmeter on the dash? If so does it show alternator is chargeing?

[Tim Bookmiller]

Your 4106 has a "starter/generator" relay -when engine starts -gen pulls one side in-other side is for starter -keeping starter from being engaged  if gen is working -check da book for adjustment

[JerryH]

Hey Barnowl:

I have an MC-8, so my input may have no bearing on your coach or issue.

But...

Ours has an air cylinder for tensioning the generator belts.  Once proper air pressure is reached, the cylinder engages.  However, in our case ... faulty air cylinder caused it not to have tension.  Didn't look like it didn't have tension, but it didn't. 

That's my $0.02.

JerryH

[lesrMC9]

see BNO board for my reply and one from Tom (Alaska)

[Barn Owl]

I want to thank everyone who is trying to help me with this problem. I know it is very hard to do much with no more information than I gave, not to mention the fact that you don't have the bus in front of you.

So here is an update:

I found a relay that is not in the drawings. It is connected to the regulator and I don't know what it is for or why it was added. If anyone has any ideas have at it. It becomes active when the starter button is pressed and then it releases (I think). It is hard to push starter buttons and try to figure out what is happening on the other side of the bus. See photo below.

The starter/generator relay seems to be functional. The book says to check the generator field input for voltage and if none is found, start looking at the generator for the problem. That input voltage was not there.

Sometimes during this the starter switch would have to be pressed several times (nothing happening) before it would take and start (not sure if it is related to the gen problem because it would start and not generate). I went through and cleaned all connection points a month ago in preparation for summer travels and haven't seen or had a problem. (From battery to starter, solenoid, etc.)

Batteries are full charge.

Now to make matters more difficult all of a sudden the problem vanished. Everything is working fine now. How am I going to find that kind of gremlin I don't know.  I will have to wait for it to happen again, but it would be my luck it will happen right in the middle of my vacation. Then it will not magically disappear and let me go home. To make matters worse, I will not have access to a computer to ask for help troubleshooting this problem.

Again thank you all for taking the time to respond. I have a feeling I will be dealing with it again soon enough.

[pvcces]

You've got something mixed up, there, Barn Owl. If there is no power at the generator field terminal, it's not the generator; the regulator is not being turned on or it is defective.

The sensing relay does that job, as I explained over on BNO. I think your symptoms could be caused by that relay. There are a number of those relays used on your coach, so there is a reason to carry a spare.

When these relays get very old, it's not uncommon for the swaged parts it the base to develope a high resistance connection. I soldered all the joints in the relay that could go bad, and I think it's been fine ever since.

The relay is just a single pole double throw magnetic switch. And it is not shown in our manual. I got a copy of the circuit from another busnut.

Good luck with your problem.

Tom Caffrey

[jjrbus]

When you are traveling you can access a computer at most librarys and universitys!

[Hi yo silver]

Barn Owl,
If you will call me at five nine one, five two one nine, I'll help if I can.  Been meaning to ask if you wanted to go to Hershey for the Bus Museum shindig anyway, but obviously, you'll be gone.
Dennis   

[Barn Owl]

Thanks Dennis, I have defiantly regained my composure and am excited again to hit the road. Everyone has been a great help. As good as the book is, I am finding out it doesn't cover every possible scenario. I couldn't do this hobby without all of your help.

Thanks Again,

Laryn Christley

[Hi yo silver]

Hope you and yours have a great and memorable vacation, Laryn! I hope to see pictures! I'm jealous....
Dennis

[Lee Bradley]

Hope you find the problem and have a great trip. What ever that relay does; it should not be in the battery compartment. Acid vapor is hard on the relay and the relay can ignite the hydrogen created by the batteries.

[Barn Owl]

Good point, I need to figure out what it does and move it. BTW, Started the bus two times today and no light. It's waiting to pop on when I pull out. LOL