Postive / Negative ground system

[transit360]

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

[Scott Peatross]

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]

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





SPONSORED LINKS

Recreational vehicles
Wanderlodge
Automotive maintenance
Recreational vehicle
dealer Used
recreational vehicles
Automotive radiators


---------------------------------
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Visit your group "WanderlodgeForum" on the web.

To unsubscribe from this group, send an email to:
WanderlodgeForum-unsubscribe@yahoogroups.com

Your use of Yahoo! Groups is subject to the Yahoo!
Terms of Service.


---------------------------------





SPONSORED LINKS
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dealer Used recreational vehicles Automotive radiators

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---------------------------------




Steve Wicker
http://www.360partybus.com
828-236-2841/301-0245

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[bluebirdsp36]

Steve,

I also have two 1995 QBREs with consecutive VIN #s. I'm converting one
and have the other for sale. Mine are both negetive grounds. All the
documentation I have I will share with you. . . Wiring diagrams, fault
code charts, operator's manual, drive train manual, etc.. I just
checked my wiring schematic which covers models through 1999 and all
are neg gnd.

Paul Cunningham
Virginia
1990 SP-36 & Two Q-Busses


--- In WanderlodgeForum@yahoogroups.com, "transit360" wrote:
> I have two Bluebird QBRE's and they are wired a little diffently.
> Thanks,
> Steve
> Two '98 Bluebird QBRE Partybuses

[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
>
>
>
>
>
> SPONSORED LINKS
>
>Recreational vehicles
> Wanderlodge
>Automotive maintenance
> Recreational vehicle
>dealer Used
>recreational vehicles
> Automotive radiators
>
>
>---------------------------------
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>
>
> Visit your group "WanderlodgeForum" on the web.
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>
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>
>
>---------------------------------
>
>
>
>
>
>SPONSORED LINKS
>Recreational vehicles Wanderlodge Automotive maintenance
>Recreational vehicle dealer Used recreational vehicles Automotive radiators
>
>---------------------------------
>YAHOO! GROUPS LINKS
>
>
> Visit your group "WanderlodgeForum" on the web.
>
> To unsubscribe from this group, send an email to:
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>
> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
>
>
>---------------------------------
>
>
>
>
>Steve Wicker
>http://www.360partybus.com
>828-236-2841/301-0245
>
>__________________________________________________
>Do You Yahoo!?
>Tired of spam? Yahoo! Mail has the best spam protection around
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[steve wicker]

That all sound right except that my 3rd wire is about a 4 gauge and on one
bus it goes from + on alternator to + on starter solenoid and on the other bus
it goes from - on alternator to a ground on the back of the starter body, which
shares a terminal with a ground strap. Thanks for the info. I'm learning!
Also, one bus is wired with an exciter wire and the other had the
alternator rebuilt so that it doesn't need the exciter wire anymore, but the
exciter wire is really small compared to the 3rd mystery wire.

Steve

Tom Warner wrote:
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



Steve Wicker
http://www.360partybus.com
828-236-2841/301-0245


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