32 volts?

[Bryan]

Plenty of times in my life, I've had cars that have alternators go bad and result in NO voltage... but I've never had the opposite..

When taking off onto an interstate, my voltage meter is jumping from 28 to 32 volts. The needle just waves at me (28 to 32 to 28 to 32 to 28) until I let off the throttle, then it returns to a steady 28. So if I baby it, there is no problem. Then... if I'm going over 65 miles and hour and hit the brake it will also do it. For example if I'm coming down a hill at 65mph or above, and hit the brakes, it will wave at me again, but if I let off the brakes and coast, it will return to a steady 28. The only other time I can get it to do it is if I do a hard down shift. I'm certain it's not simply a gauge issue because I can hear the driver air conditioner fans speeding up and slowing down as the needle waves at me.

Any thoughts, comments, suggestions?

[eagle19952]

Something big and drawing a huge overload...like a motor... shorting on one portion of rotation... maybe the alternator itself...

[luvrbus]

It's losing the ground between the alternator and voltage regulator sounds like to me

[Bryan]

Could you describe to me what a voltage regulator looks like? I will check for loose connections.

[RJ]

Bryan -

Which coach are you talking about?  The Prevost or the GMC?

Not sure if GM kept the voltage regulator in the same spot on the 4107s as they did on the 4106s, but if they did, it's on the back (axle) wall of the rear baggage bin.  A vertically-ribbed black box approximately 4"x9" with a big screwdriver slot in the middle.  (Maybe they moved it to the battery compartment?  Or to the rear electrical compartment behind the RR wheel?)  You'll have to poke around until you find it.  When you do, make sure you disconnect the chassis batteries so you don't spark any surprises while checking connections!

Can't help on the where the regulator is on a Prevost, unfortunately, but it would look similar to the GM's.

FWIW & HTH. . .

[Bryan]

Thank you guys! I'm sorry I probably should have specified... this post for for the Prevost. Thanks for all your input and suggestions!

[buswarrior]

Dash gauge?

Use your multimeter to confirm there really is a problem.

One of the biggest Chhicken Littles for a busnut is a dash gauge suggesting the sky is falling...

happy coaching!
buswarrior

[Jon]

Whatever  the cause, bad regulator, bad ground, etc. it is an issue that cannot be ignored. It can lead to expensive problems.

If the coach is equipped with a Vanner monitor I am surprised it wasn't lighting up lights on the dash.

[luvrbus]

If you have one of the old style a big black box with cooling fins spend the bucks and buy the 1941463 regulator they have voltage over protection,short circuit protection and a automatic shut down with a reset button,the latter is something needed with a friggn Vanner.The regulator should be in the battery compartment along with the Vanner   

[Bryan]

Either of these the regulator?

[thomasinnv]

Nope. Thats the vanner and control box

[luvrbus]

Nope it will have 4 terminals either will be 4 inches wide x 8 inches long with cooling fins or a gray box 4x4x1 with 4 terminals mounted below the main circuit breakers on the left side   

[Bryan]

https://vimeo.com/175157275

[Bryan]

I took a short video in my previous post. Do you see the regulator?

[eagle19952]

I took a short video in my previous post. Do you see the regulator?

no