No power for split second... BUMP!

[Bryan]

Hey guys, hope everyone has been doing well. I picked up my bus from the shop last night and I now have power steering! It's great! The bad news is that on the way home, the clutch started messing up, now it is stuck in my driveway and I have the mechanic coming to look at it this weekend. It won't budge...

but something else happened on the way home last night that is really bothering me that I wanted to ask you guys about. I ran over some railroad tracks, and for a half of a second the entire bus turned off, the head lights even turned off, on the dash, the "NO CHARGE" light came on for that split second too. Then before the second was over everything was back to normal like it never happened. This happened also when I hit a pothole in the road. Any suggestions? Thanks for your time! 

[Lin]

I guess the first place I would look at are things connected with the main switch circuit.  The switch itself could be faulty, a connection could be loose, a relay could be weak, a ground could be loose.  It is sometimes difficult to trace intermittent electrical issues since everything you test can work just fine.

[eagle19952]

Main battery grounds, and battery terminals would be my first look see's.

[Lin]

I stand corrected.  Eagle is right.  My suggestion would be a second place to look.

[chessie4905]

   My first guess on this is(unless it has happened before) that something in the engine compartment was unhooked or loosened/ damaged during the power steering installation and missed being re-tightened.

[luvrbus]

A loose connection on the battery terminal at the starter is where I would begin,it's not a ground the alternator will go full blast when the ground is lost   

[bevans6]

I was all set to call out the main battery disconnect switch when Clifford posted about the alternator running away (which it can do whenever the regulator can't see battery voltage and therefore leaves the field coil on, as I understand it) and I pulled some schematics.  Now this is based on MCI so take with a grain of salt.  The alternator output goes directly to all of the main power buses and does not go through the master battery disconnect switch except to reach the batteries.  If the master disconnect switch burped, you would have seen the voltage spike for a second, not drop off, unless you have other batteries in the circuit (as I do, my house batteries are connected to the AC power bus).  So I now think it is a self-resetting relay popping, probably the one that feeds your master on/off switch (again relating this to how MCI's are wired).  Could be doing it's job protecting against a temporary short circuit, could be a bad relay. 

Brian

[baker4106]

My 4106 has been converted to a key start and run and after several years when I hit a bump it would do that.   Found the key switch bad and shutting power off to the shut down solenoid causing it to shut down momentarily.