12 volts on regulator ground wire?

[amcme]

Hi everyone, my name is Al and I'm new to the forum. I recently was given a 1980 xs400 and have begun the slow process of bringing it back to life.

My biggest problem at the moment is I was getting 12 volts on the ground circuit in the wiring harness. At this point I've determined that the voltage regulator is spitting out 12 volts through the black ground wire and engergizing the entire ground circuit. I got a new used regulator (not guaranteed to be any good) from a salvage place and still had the same problem.

My questions are as follows: I'm not crazy right? With the key on, bike not running, I should not be getting 12+ volts off the black ground wire on the regulator, correct?? What are the odds I ended up with two bad regulators with the same problem? I want to make sure I'm not missing something stupid before I spend money on an aftermarket regulator.

I genuinely appreciate any help that anyone can provide. So glad I found this site!!

 

[1979XS4002-F]

I just spent days working on my charging sys... The black should be grounded and if its getting 12v thru it there is probably a direct short somewhere. Is all or most of your wiring stock, maybe take some pics and post them for aid in troubleshooting. Welcome to the forum...trust me when I say it is AWESOME

 

[1979XS4002-F]

Also, do a search in the forum search bar for napa voltage regulator...its my last thread..if your vreg is truly bad napa has them for cheap!

 

[amcme]

I pulled the wire terminals out of the plastic plug on the regulator and connected the green and brown wires individually into the harness, but left the black ground wire unhooked. If I'm getting 12 volts from that wire straight out of the regulator, that must mean there's a direct short within the regulator right?

Thanks for the input!

p.s. wiring is all stock

 

[1979XS4002-F]

If you disconnected your vreg plug then the 12v your getting is from your bike..not the disconnected vreg

 

[amcme]

green and brown vreg wires are connected, only the black is not. I'm getting 12v from the disconnected black wire. There is no voltage on the bike ground.

 

[1979XS4002-F]

The vreg bypass test should be executed as follows 1) run a jumper from back of plug for vreg touching green wire and mate to (+)battery. 2) run a jumper from black wire(back of plug) to (-) battery leave vreg plug attached and start bike with multimeter on battery..rev bike to 3k and let idle volts should climb and receed as throttle is manipulated

 

[1979XS4002-F]

Ok, lets start at the beginning.. Why are you replacing the vreg? Does your volts not climb when throttle is manipulated?

 

[amcme]

The bike is not currently running. The only reason I'm replacing the regulator is because I traced the positive ground issue back to that component.

 

[1979XS4002-F]

The vreg blk wire is feed/ a direct line to the field coil..have you pulled your stator cover off and looked for shorts/exposed wires there?

 

[skervey35]

Does anyone know what the black/red or brown wire running from the regulator does? I am hooking up a new regulator and just want to be shore on what it does before i wire it up and fire the bike back up. Here is a link to my post

http://www.xs400.com/forum/showthread.php?t=8445