Postive / Negative ground system

[Tom Warner]

You have a negative ground system. As far as I know Bluebird never
made a postive ground electrical system.

You should have a red wire attached to the Plus terminal of your
alternator and going to either the positive terminal of your battery
or the positive terminal insulated fromo the chassis and then to the
Plus terminal of the battery.

The black wire is attached to the minus(negative( terminal of the
alternator and then to ground. Sometimes it goes to a stud on the
starter and then a ground braid to the chassis.

The third wire is probably a sense wire and goes from the internal
voltage regulator stud on the outside of the alternator and then to
the positive battery terminal. It senses the true voltage from the
battery and NOT the voltage across the positive and negative
terminals of the alternator.

tom
1982 FC35
Vernon Center,NY

At 04:01 AM 9/18/2005, you wrote:
> The 2nd alternator does not have anything attached to the
> positive alternator terminal but the positive battery cable.
> There's only 3 wires to each alternator. A definate positive and
> negative cable from the battery to alternator, and the 3rd smaller wire.
>
>Steve
>
>Scott Peatross <slpeatross@...> wrote:
>Sounds like they are both negative ground systems. The
>"ground" of a system is determined by which terminal
>of the battery is connected to the frame/body/engine.
>So in a negative ground system, the negative side of
>the battery is connected to the frame, and all
>positive connections must be isolated from the frame.
>
>Notice that one alternator has the 3rd wire positive
>to positive, the other has the third wire negative to
>negative. No problem there. Does the 2nd alternator
>have anything connected to the positive connection?
>
>Scott Peatross
>'87 PT40
>
>--- transit360 wrote:
>
>
>---------------------------------
> I have two Bluebird QBRE's and they are wired a
>little diffently.
>In short, how can I tell if someone has wired one bus
>or the other
>for a positive or negative ground system? Please only
>advise if you
>can supply me with some tests I can run with a meter
>or if you've
>had experience with electrical systems. I'm running
>inverters and
>they've warned NOT to use these with a positive ground
>system.
> The reason I ask is because there is a + and -
>terminal on the
>battery hooked likewise to the alternator. Then I have
>a 3rd wire,
>probably 6 gauge that runs to the starter.
> NOW, on the 1st bus this 3rd wire runs from the
>+ on the
>alternator to the starter SOLENOID, where is shares a
>main + feed
>from the battery.
> On the 2nd bus, this same wire runs from the -
>side of the
>alternator to a ground stud of the back of the starter
>BODY, where
>is shares this stud with a main ground strap. Is this
>a postive
>ground system?
> I only discovered this after on the 2nd bus I
>hooked this
>wire to the + side of the alternator to match the
>other bus, only to
>have it heat up. I didn't know why until I traced the
>wire to the
>ground stud on the starter body.
> Would anyone know of any reason why a mechanic
>would do this,
>especially on two identical buses? And more
>importantly, how can I
>wire this system up to guarantee that it's the typical
>negative
>ground system that I need? Or is this system still a
>negative ground
>anyways?? I have a little electrical knowledge but I'm
>stumped and I
>really don't want to damage my new inverters.
>
>Thanks,
>Steve
>Two '98 Bluebird QBRE Partybuses
>
>
>
>
>
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>Steve Wicker
>http://www.360partybus.com
>828-236-2841/301-0245
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