Voltage unstable
12-15-2006 | 03:25 AM
#1
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Posts: n/a
Voltage unstable
During night driving I have noticed that the head lights vary in
brightness. They brighten up at about 2500 to 3000 revs and dim when
the revs drop. But when in say 4th or 5th gear at about 1500
revs(Diesel model) and I lift off the accrelator the lights
brightenup?. Strange. This will voltage varation only happens AFTER
the engine has warmed up. The brightness varation is also noted if you
over-ride the interior lights. My garage has replaced the control unit
but no change. Any suggestions. The battery and alternator have been
FULLY checked out and found to be OK.
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brightness. They brighten up at about 2500 to 3000 revs and dim when
the revs drop. But when in say 4th or 5th gear at about 1500
revs(Diesel model) and I lift off the accrelator the lights
brightenup?. Strange. This will voltage varation only happens AFTER
the engine has warmed up. The brightness varation is also noted if you
over-ride the interior lights. My garage has replaced the control unit
but no change. Any suggestions. The battery and alternator have been
FULLY checked out and found to be OK.
--
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12-15-2006 | 07:21 AM
#2
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Re: Voltage unstable
"yourpete" <none@000.com> wrote in message
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop. But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accrelator the lights
> brightenup?. Strange. This will voltage varation only happens AFTER
> the engine has warmed up. The brightness varation is also noted if you
> over-ride the interior lights. My garage has replaced the control unit
> but no change. Any suggestions. The battery and alternator have been
> FULLY checked out and found to be OK.
>
It would help to know what year and model.
Mike
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop. But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accrelator the lights
> brightenup?. Strange. This will voltage varation only happens AFTER
> the engine has warmed up. The brightness varation is also noted if you
> over-ride the interior lights. My garage has replaced the control unit
> but no change. Any suggestions. The battery and alternator have been
> FULLY checked out and found to be OK.
>
It would help to know what year and model.
Mike
12-15-2006 | 07:21 AM
#3
Guest
Posts: n/a
Re: Voltage unstable
"yourpete" <none@000.com> wrote in message
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop. But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accrelator the lights
> brightenup?. Strange. This will voltage varation only happens AFTER
> the engine has warmed up. The brightness varation is also noted if you
> over-ride the interior lights. My garage has replaced the control unit
> but no change. Any suggestions. The battery and alternator have been
> FULLY checked out and found to be OK.
>
It would help to know what year and model.
Mike
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop. But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accrelator the lights
> brightenup?. Strange. This will voltage varation only happens AFTER
> the engine has warmed up. The brightness varation is also noted if you
> over-ride the interior lights. My garage has replaced the control unit
> but no change. Any suggestions. The battery and alternator have been
> FULLY checked out and found to be OK.
>
It would help to know what year and model.
Mike
12-15-2006 | 07:21 AM
#4
Guest
Posts: n/a
Re: Voltage unstable
"yourpete" <none@000.com> wrote in message
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop. But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accrelator the lights
> brightenup?. Strange. This will voltage varation only happens AFTER
> the engine has warmed up. The brightness varation is also noted if you
> over-ride the interior lights. My garage has replaced the control unit
> but no change. Any suggestions. The battery and alternator have been
> FULLY checked out and found to be OK.
>
It would help to know what year and model.
Mike
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop. But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accrelator the lights
> brightenup?. Strange. This will voltage varation only happens AFTER
> the engine has warmed up. The brightness varation is also noted if you
> over-ride the interior lights. My garage has replaced the control unit
> but no change. Any suggestions. The battery and alternator have been
> FULLY checked out and found to be OK.
>
It would help to know what year and model.
Mike
12-15-2006 | 07:21 AM
#5
Guest
Posts: n/a
Re: Voltage unstable
"yourpete" <none@000.com> wrote in message
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop. But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accrelator the lights
> brightenup?. Strange. This will voltage varation only happens AFTER
> the engine has warmed up. The brightness varation is also noted if you
> over-ride the interior lights. My garage has replaced the control unit
> but no change. Any suggestions. The battery and alternator have been
> FULLY checked out and found to be OK.
>
It would help to know what year and model.
Mike
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop. But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accrelator the lights
> brightenup?. Strange. This will voltage varation only happens AFTER
> the engine has warmed up. The brightness varation is also noted if you
> over-ride the interior lights. My garage has replaced the control unit
> but no change. Any suggestions. The battery and alternator have been
> FULLY checked out and found to be OK.
>
It would help to know what year and model.
Mike
12-15-2006 | 02:25 PM
#6
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Posts: n/a
Re: Re: Voltage unstable
Accord 2.2 diesel 4 door saloon. June 2004
"Michael Pardee" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop. But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accrelator the lights
> > brightenup?. Strange. This will voltage varation only
> happens AFTER
> > the engine has warmed up. The brightness varation is also
> noted if you
> > over-ride the interior lights. My garage has replaced the
> control unit
> > but no change. Any suggestions. The battery and alternator
> have been
> > FULLY checked out and found to be OK.
> >
> It would help to know what year and model.
>
> Mike
--
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"Michael Pardee" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop. But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accrelator the lights
> > brightenup?. Strange. This will voltage varation only
> happens AFTER
> > the engine has warmed up. The brightness varation is also
> noted if you
> > over-ride the interior lights. My garage has replaced the
> control unit
> > but no change. Any suggestions. The battery and alternator
> have been
> > FULLY checked out and found to be OK.
> >
> It would help to know what year and model.
>
> Mike
--
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12-15-2006 | 02:25 PM
#7
Guest
Posts: n/a
Re: Re: Voltage unstable
Accord 2.2 diesel 4 door saloon. June 2004
"Michael Pardee" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop. But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accrelator the lights
> > brightenup?. Strange. This will voltage varation only
> happens AFTER
> > the engine has warmed up. The brightness varation is also
> noted if you
> > over-ride the interior lights. My garage has replaced the
> control unit
> > but no change. Any suggestions. The battery and alternator
> have been
> > FULLY checked out and found to be OK.
> >
> It would help to know what year and model.
>
> Mike
--
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"Michael Pardee" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop. But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accrelator the lights
> > brightenup?. Strange. This will voltage varation only
> happens AFTER
> > the engine has warmed up. The brightness varation is also
> noted if you
> > over-ride the interior lights. My garage has replaced the
> control unit
> > but no change. Any suggestions. The battery and alternator
> have been
> > FULLY checked out and found to be OK.
> >
> It would help to know what year and model.
>
> Mike
--
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12-15-2006 | 02:25 PM
#8
Guest
Posts: n/a
Re: Re: Voltage unstable
Accord 2.2 diesel 4 door saloon. June 2004
"Michael Pardee" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop. But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accrelator the lights
> > brightenup?. Strange. This will voltage varation only
> happens AFTER
> > the engine has warmed up. The brightness varation is also
> noted if you
> > over-ride the interior lights. My garage has replaced the
> control unit
> > but no change. Any suggestions. The battery and alternator
> have been
> > FULLY checked out and found to be OK.
> >
> It would help to know what year and model.
>
> Mike
--
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"Michael Pardee" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop. But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accrelator the lights
> > brightenup?. Strange. This will voltage varation only
> happens AFTER
> > the engine has warmed up. The brightness varation is also
> noted if you
> > over-ride the interior lights. My garage has replaced the
> control unit
> > but no change. Any suggestions. The battery and alternator
> have been
> > FULLY checked out and found to be OK.
> >
> It would help to know what year and model.
>
> Mike
--
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12-15-2006 | 02:25 PM
#9
Guest
Posts: n/a
Re: Re: Voltage unstable
Accord 2.2 diesel 4 door saloon. June 2004
"Michael Pardee" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop. But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accrelator the lights
> > brightenup?. Strange. This will voltage varation only
> happens AFTER
> > the engine has warmed up. The brightness varation is also
> noted if you
> > over-ride the interior lights. My garage has replaced the
> control unit
> > but no change. Any suggestions. The battery and alternator
> have been
> > FULLY checked out and found to be OK.
> >
> It would help to know what year and model.
>
> Mike
--
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"Michael Pardee" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop. But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accrelator the lights
> > brightenup?. Strange. This will voltage varation only
> happens AFTER
> > the engine has warmed up. The brightness varation is also
> noted if you
> > over-ride the interior lights. My garage has replaced the
> control unit
> > but no change. Any suggestions. The battery and alternator
> have been
> > FULLY checked out and found to be OK.
> >
> It would help to know what year and model.
>
> Mike
--
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12-15-2006 | 04:15 PM
#10
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Posts: n/a
Re: Voltage unstable
"yourpete" <none@000.com> wrote in message
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop.
OK, lets look at what causes a visible variation: change in voltage. Since
you say the alternator and battery have tested OK, then its likely a
mechanical rather than an electrical problem.
What causes an alternator to vary voltage? A slipping belt is the usual
reason. A bad ground is another.
> But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accelerator the lights
> brighten up...
Have a good look at all the alternator mounting brackets. Is anything loose?
eg the main pivot bolt on to the block. Check all the engine block to
chassis ground links.
Is the crank pulley loose or is a two part balancer type? Could be the
pulley is separating and moving the belt around causing slipage or lateral
movement in the alternator.
SD
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop.
OK, lets look at what causes a visible variation: change in voltage. Since
you say the alternator and battery have tested OK, then its likely a
mechanical rather than an electrical problem.
What causes an alternator to vary voltage? A slipping belt is the usual
reason. A bad ground is another.
> But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accelerator the lights
> brighten up...
Have a good look at all the alternator mounting brackets. Is anything loose?
eg the main pivot bolt on to the block. Check all the engine block to
chassis ground links.
Is the crank pulley loose or is a two part balancer type? Could be the
pulley is separating and moving the belt around causing slipage or lateral
movement in the alternator.
SD
12-15-2006 | 04:15 PM
#11
Guest
Posts: n/a
Re: Voltage unstable
"yourpete" <none@000.com> wrote in message
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop.
OK, lets look at what causes a visible variation: change in voltage. Since
you say the alternator and battery have tested OK, then its likely a
mechanical rather than an electrical problem.
What causes an alternator to vary voltage? A slipping belt is the usual
reason. A bad ground is another.
> But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accelerator the lights
> brighten up...
Have a good look at all the alternator mounting brackets. Is anything loose?
eg the main pivot bolt on to the block. Check all the engine block to
chassis ground links.
Is the crank pulley loose or is a two part balancer type? Could be the
pulley is separating and moving the belt around causing slipage or lateral
movement in the alternator.
SD
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop.
OK, lets look at what causes a visible variation: change in voltage. Since
you say the alternator and battery have tested OK, then its likely a
mechanical rather than an electrical problem.
What causes an alternator to vary voltage? A slipping belt is the usual
reason. A bad ground is another.
> But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accelerator the lights
> brighten up...
Have a good look at all the alternator mounting brackets. Is anything loose?
eg the main pivot bolt on to the block. Check all the engine block to
chassis ground links.
Is the crank pulley loose or is a two part balancer type? Could be the
pulley is separating and moving the belt around causing slipage or lateral
movement in the alternator.
SD
12-15-2006 | 04:15 PM
#12
Guest
Posts: n/a
Re: Voltage unstable
"yourpete" <none@000.com> wrote in message
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop.
OK, lets look at what causes a visible variation: change in voltage. Since
you say the alternator and battery have tested OK, then its likely a
mechanical rather than an electrical problem.
What causes an alternator to vary voltage? A slipping belt is the usual
reason. A bad ground is another.
> But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accelerator the lights
> brighten up...
Have a good look at all the alternator mounting brackets. Is anything loose?
eg the main pivot bolt on to the block. Check all the engine block to
chassis ground links.
Is the crank pulley loose or is a two part balancer type? Could be the
pulley is separating and moving the belt around causing slipage or lateral
movement in the alternator.
SD
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop.
OK, lets look at what causes a visible variation: change in voltage. Since
you say the alternator and battery have tested OK, then its likely a
mechanical rather than an electrical problem.
What causes an alternator to vary voltage? A slipping belt is the usual
reason. A bad ground is another.
> But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accelerator the lights
> brighten up...
Have a good look at all the alternator mounting brackets. Is anything loose?
eg the main pivot bolt on to the block. Check all the engine block to
chassis ground links.
Is the crank pulley loose or is a two part balancer type? Could be the
pulley is separating and moving the belt around causing slipage or lateral
movement in the alternator.
SD
12-15-2006 | 04:15 PM
#13
Guest
Posts: n/a
Re: Voltage unstable
"yourpete" <none@000.com> wrote in message
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop.
OK, lets look at what causes a visible variation: change in voltage. Since
you say the alternator and battery have tested OK, then its likely a
mechanical rather than an electrical problem.
What causes an alternator to vary voltage? A slipping belt is the usual
reason. A bad ground is another.
> But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accelerator the lights
> brighten up...
Have a good look at all the alternator mounting brackets. Is anything loose?
eg the main pivot bolt on to the block. Check all the engine block to
chassis ground links.
Is the crank pulley loose or is a two part balancer type? Could be the
pulley is separating and moving the belt around causing slipage or lateral
movement in the alternator.
SD
news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> During night driving I have noticed that the head lights vary in
> brightness. They brighten up at about 2500 to 3000 revs and dim when
> the revs drop.
OK, lets look at what causes a visible variation: change in voltage. Since
you say the alternator and battery have tested OK, then its likely a
mechanical rather than an electrical problem.
What causes an alternator to vary voltage? A slipping belt is the usual
reason. A bad ground is another.
> But when in say 4th or 5th gear at about 1500
> revs(Diesel model) and I lift off the accelerator the lights
> brighten up...
Have a good look at all the alternator mounting brackets. Is anything loose?
eg the main pivot bolt on to the block. Check all the engine block to
chassis ground links.
Is the crank pulley loose or is a two part balancer type? Could be the
pulley is separating and moving the belt around causing slipage or lateral
movement in the alternator.
SD
12-15-2006 | 08:25 PM
#14
Guest
Posts: n/a
Re: Re: Voltage unstable
I have thought of this route BUT this problem ONLY happens after the
engine has warmed up. This leads me towards an electrical problem and
your thoughts about a poor earth will be checked. If a poor earth
should this not have shown up when the battery and alternator were
checked?
The unit that controls electrics has just been replaced with no change
to the problem
"Stewart DIBBS" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop.
>
> OK, lets look at what causes a visible variation: change in
> voltage. Since
> you say the alternator and battery have tested OK, then its
> likely a
> mechanical rather than an electrical problem.
>
> What causes an alternator to vary voltage? A slipping belt is
> the usual
> reason. A bad ground is another.
>
> > But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accelerator the lights
> > brighten up...
>
> Have a good look at all the alternator mounting brackets. Is
> anything loose?
> eg the main pivot bolt on to the block. Check all the engine
> block to
> chassis ground links.
>
> Is the crank pulley loose or is a two part balancer type?
> Could be the
> pulley is separating and moving the belt around causing
> slipage or lateral
> movement in the alternator.
>
> SD
--
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engine has warmed up. This leads me towards an electrical problem and
your thoughts about a poor earth will be checked. If a poor earth
should this not have shown up when the battery and alternator were
checked?
The unit that controls electrics has just been replaced with no change
to the problem
"Stewart DIBBS" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop.
>
> OK, lets look at what causes a visible variation: change in
> voltage. Since
> you say the alternator and battery have tested OK, then its
> likely a
> mechanical rather than an electrical problem.
>
> What causes an alternator to vary voltage? A slipping belt is
> the usual
> reason. A bad ground is another.
>
> > But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accelerator the lights
> > brighten up...
>
> Have a good look at all the alternator mounting brackets. Is
> anything loose?
> eg the main pivot bolt on to the block. Check all the engine
> block to
> chassis ground links.
>
> Is the crank pulley loose or is a two part balancer type?
> Could be the
> pulley is separating and moving the belt around causing
> slipage or lateral
> movement in the alternator.
>
> SD
--
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Articles individually verified to usenet standards. Visit URL to contact author/report abuse
Thread archive: http://www.AutoBoardz.com/Voltage-un...ict200609.html
12-15-2006 | 08:25 PM
#15
Guest
Posts: n/a
Re: Re: Voltage unstable
I have thought of this route BUT this problem ONLY happens after the
engine has warmed up. This leads me towards an electrical problem and
your thoughts about a poor earth will be checked. If a poor earth
should this not have shown up when the battery and alternator were
checked?
The unit that controls electrics has just been replaced with no change
to the problem
"Stewart DIBBS" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop.
>
> OK, lets look at what causes a visible variation: change in
> voltage. Since
> you say the alternator and battery have tested OK, then its
> likely a
> mechanical rather than an electrical problem.
>
> What causes an alternator to vary voltage? A slipping belt is
> the usual
> reason. A bad ground is another.
>
> > But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accelerator the lights
> > brighten up...
>
> Have a good look at all the alternator mounting brackets. Is
> anything loose?
> eg the main pivot bolt on to the block. Check all the engine
> block to
> chassis ground links.
>
> Is the crank pulley loose or is a two part balancer type?
> Could be the
> pulley is separating and moving the belt around causing
> slipage or lateral
> movement in the alternator.
>
> SD
--
Posted at author's request, using http://www.AutoBoardz.com interface
Articles individually verified to usenet standards. Visit URL to contact author/report abuse
Thread archive: http://www.AutoBoardz.com/Voltage-un...ict200609.html
engine has warmed up. This leads me towards an electrical problem and
your thoughts about a poor earth will be checked. If a poor earth
should this not have shown up when the battery and alternator were
checked?
The unit that controls electrics has just been replaced with no change
to the problem
"Stewart DIBBS" wrote
> "yourpete" <none@000.com> wrote in message
> news:951271_8f4af7ca4a55d1930a8829b577d7fdf6@autob oardz.com...
> > During night driving I have noticed that the head lights
> vary in
> > brightness. They brighten up at about 2500 to 3000 revs and
> dim when
> > the revs drop.
>
> OK, lets look at what causes a visible variation: change in
> voltage. Since
> you say the alternator and battery have tested OK, then its
> likely a
> mechanical rather than an electrical problem.
>
> What causes an alternator to vary voltage? A slipping belt is
> the usual
> reason. A bad ground is another.
>
> > But when in say 4th or 5th gear at about 1500
> > revs(Diesel model) and I lift off the accelerator the lights
> > brighten up...
>
> Have a good look at all the alternator mounting brackets. Is
> anything loose?
> eg the main pivot bolt on to the block. Check all the engine
> block to
> chassis ground links.
>
> Is the crank pulley loose or is a two part balancer type?
> Could be the
> pulley is separating and moving the belt around causing
> slipage or lateral
> movement in the alternator.
>
> SD
--
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Articles individually verified to usenet standards. Visit URL to contact author/report abuse
Thread archive: http://www.AutoBoardz.com/Voltage-un...ict200609.html