Fuse problem with Nissan Sunny 1.4 keeps blowing out (need tips)

A while ago my right rear light blowed out a fuse, after replacing the bulb
and fuse there was no problem for a week
But now the same fuse keeps blowing out and the rear right light, inluding
the 2 licences plate lights,
and the 2 city lights on front,and the dashboard light are out.
I meassure a major shortage on the fuse box even when i disconnect all
connectors to all lights
and removing the dashboard panel
(so there is no shorting to the chassis in them) and removed the relays from
their socket.
Also on the internet pages they suggested that it could be the radio
connection but either this is not the problem.

My question is : is there maybe a diode in the circuit for the lights (for
the relay) and where is this located
Do i have to dismantle the fuse box to get closer to the cause of this.
Or is there anyone who have had a similar problem and can give me a tip
where to look at.
Or will my greatest nightmare come true and do i have to strip my car for
all the wiring from front to back to look for damaged wires.
Thanks in advance for replying with serious tips about this.

Ronald (sorry for any bad english in my post, i am a simple dutchie)

A while ago my right rear light blowed out a fuse, after replacing the
bulb
and fuse there was no problem for a week
But now the same fuse keeps blowing out and the rear right light, inluding
the 2 licences plate lights,
and the 2 city lights on front,and the dashboard light are out.
I meassure a major shortage on the fuse box even when i disconnect all
connectors to all lights
and removing the dashboard panel
(so there is no shorting to the chassis in them) and removed the relays
from
their socket.
Also on the internet pages they suggested that it could be the radio
connection but either this is not the problem.

My question is : is there maybe a diode in the circuit for the lights (for
the relay) and where is this located
Do i have to dismantle the fuse box to get closer to the cause of this.
Or is there anyone who have had a similar problem and can give me a tip
where to look at.
Or will my greatest nightmare come true and do i have to strip my car for
all the wiring from front to back to look for damaged wires.
Thanks in advance for replying with serious tips about this.

(I could do this in Dutch, but that would be impolite in an English language
group, right)
Not sure what a Sunny looks like but the following is generic enough to
apply to pretty much any car:

Do you have a schematic to your car? If so, make sure that you indeed
unplugged everything on the leg of that fuse.
Relays do often contain diodes (at least, they are supposed to) but the ones
I've seen usually have them internal to the relay. Those particular diodes
are there to absorb back EMF - this is when the field of the relay
collapses. The coil basically generates a voltage and this is shunted by
this diode. It serves as a protection to whatever drives the relay.
These diodes don't need to be super beefy and are often not large enough to
blow 10A slow blow fuses - the diode usually opens first.
It could be a diode, but I'd say it is far less likely than a wire short
somewhere.

Do any of the wires attached to this fuse run near the engine? Perhaps some
insulation burned off and it is now shorting to ground.

If your multimeter is sensitive enough, you could determine about where the
short is located by probing on all sockets on that leg - it is physcially
closest to where the resistance is the lowest.

That's about as serious as "deze weggelopen nederlander (Connecticut, VS)"
can be

Ik hoop dat je het probleem snel vindt.

Remco

"remco" <whybcuzREMOVE (AT) THISyahoo (DOT) com> schreef in bericht
news:vLW8e.2799$sG3.1402 (AT) fe09 (DOT) lga...

A while ago my right rear light blowed out a fuse, after replacing the
bulb
and fuse there was no problem for a week
But now the same fuse keeps blowing out and the rear right light,
inluding
the 2 licences plate lights,
and the 2 city lights on front,and the dashboard light are out.
I meassure a major shortage on the fuse box even when i disconnect all
connectors to all lights
and removing the dashboard panel
(so there is no shorting to the chassis in them) and removed the relays
from
their socket.
Also on the internet pages they suggested that it could be the radio
connection but either this is not the problem.

My question is : is there maybe a diode in the circuit for the lights
(for
the relay) and where is this located
Do i have to dismantle the fuse box to get closer to the cause of this.
Or is there anyone who have had a similar problem and can give me a tip
where to look at.
Or will my greatest nightmare come true and do i have to strip my car for
all the wiring from front to back to look for damaged wires.
Thanks in advance for replying with serious tips about this.

(I could do this in Dutch, but that would be impolite in an English
language
group, right)
Not sure what a Sunny looks like but the following is generic enough to
apply to pretty much any car:

Do you have a schematic to your car? If so, make sure that you indeed
unplugged everything on the leg of that fuse.
Relays do often contain diodes (at least, they are supposed to) but the
ones
I've seen usually have them internal to the relay. Those particular diodes
are there to absorb back EMF - this is when the field of the relay
collapses. The coil basically generates a voltage and this is shunted by
this diode. It serves as a protection to whatever drives the relay.
These diodes don't need to be super beefy and are often not large enough
to
blow 10A slow blow fuses - the diode usually opens first.
It could be a diode, but I'd say it is far less likely than a wire short
somewhere.

Do any of the wires attached to this fuse run near the engine? Perhaps
some
insulation burned off and it is now shorting to ground.

If your multimeter is sensitive enough, you could determine about where
the
short is located by probing on all sockets on that leg - it is physcially
closest to where the resistance is the lowest.

That's about as serious as "deze weggelopen nederlander (Connecticut, VS)"
can be

Ik hoop dat je het probleem snel vindt.

Remco

Bedankt voor reactie Remco / Thanks for quick reaction Remco

As reaction on your questions, No unfortunally i don't have any schematics
of the car or a diagram
It would make it a lot easyer to pinpoint the fault
About the Back emf of the Diode i know that they are there for that reason,
i was a Broadcast Engineer in the past
and have a little knowhow about electronics, It is good to know now that
those diode are inside the relays and not
mounted on the back of the socket (it would be a hell to dismantle the fuse
box to check this)
About the wires near to the engine, i have checked all the wirebundles
(kabelbomen) and pulled on them where they
vanished in the car in their tules (this was to check that there was not a
cable rubbing to the chassis)
and as far as i could see there was no blank cable to the body, so my gues
is that i have to open the part beside the chairs
to see if there is a malfunction in the bundle from front to the rear.
And thank you for the measuring tip (i think my MultiMeter is sensitive
enough to determine the location)
I will try to do this tomorrow it is now 1.45 in the morning over here in
the netherlands (Huizen)

By the way is there a internet site where i can see the wiring diagram of my
car?

Gegroet en bedankt weggelopen nederlander van een vastgeroeste klomp in het
kikkerland
Mocht ik iets vinden dan laat ik het je weten / Thanks for everything

Bedankt voor reactie Remco / Thanks for quick reaction Remco
As reaction on your questions, No unfortunally i don't have any schematics
of the car or a diagram
It would make it a lot easyer to pinpoint the fault
About the Back emf of the Diode i know that they are there for that
reason,
i was a Broadcast Engineer in the past
and have a little knowhow about electronics, It is good to know now that
those diode are inside the relays and not
mounted on the back of the socket (it would be a hell to dismantle the
fuse
box to check this)
About the wires near to the engine, i have checked all the wirebundles
(kabelbomen) and pulled on them where they
vanished in the car in their tules (this was to check that there was not a
cable rubbing to the chassis)
and as far as i could see there was no blank cable to the body, so my gues
is that i have to open the part beside the chairs
to see if there is a malfunction in the bundle from front to the rear.
And thank you for the measuring tip (i think my MultiMeter is sensitive
enough to determine the location)
I will try to do this tomorrow it is now 1.45 in the morning over here in
the netherlands (Huizen)

By the way is there a internet site where i can see the wiring diagram of
my
car?

Hi Ronald.

Good - glad to see you have a full grasp on electrical stuff. Broadcast
engineer? Very cool! Years ago I was involved with broadcasting, but not the
strictly legal kind It was _the_ thing to do as teenagers in Denhaag in
the 70s. We had loads of fun playing cat and mouse with the RCD.

Again, let me restress that the cars I've worked on had those diodes on the
inside of the relays. Not sure what the practice is on cars made for the
European market. Most likely those diodes would still be blown open once
they failed shorted, one would imagine, with 10A being allowed to go through
them.

I am not at all familiar with you model -- the names here are quite
different and suspect most models are as well.
Checking the schematic on my Altima (a 2.2L 4 cyl) and an older manual on a
Sentra (a 1.8L 4 cyl), it seems like they use interconnects to tie all
separate legs together. I'd imagine Nissan uses a similar scheme on your
car.
Perhaps you can figure out where these interconnects are and temporarily
disconnect them so isolate what portion of the tree it is coming from.
Without a schematic it will be a bit of a trick, but could be done. The
easiest disconnect to start with might be the light switch - I am assuming
it is on the steering column.

De hartelijke groeten vanuit Bridgeport, Connecticut.

Remco

In message <UkZ8e.3606$ZQ1.2472 (AT) fe11 (DOT) lga>, remco
<whybcuzREMOVE (AT) THISyahoo (DOT) com> writes

- the names here are quite different and suspect most models are as
well. Checking the schematic on my Altima (a 2.2L 4 cyl) and an older
manual on a Sentra (a 1.8L 4 cyl)
In England the name Sunny is model B13/N14. Don't know if it's the

same model as the Netherlands.
--
Clive.

Thanks - I am Dutch but live in the US. Our names/models might be
totally different.
Remco

I'm an electronics engineer, and IMHO a shorted relay diode may or may not
blow open after going short. The problem is that the fuse will probably
blow before the diode gets hot enough to blow open. About a 50/50 call I
would say. If the relays can be swapped do that, then if a relay is at
fault a different fuse will blow. Otherwise just use a meter to measure the
coil resistance, which should read tens to hundreds of ohms, not a short.

I had a car (it may have been an earlier Sunny funny enough) that blew a
fuse every few drives, taking out various lights etc, it turned out to be a
seized radiator fan motor on the same circuit causing an overload once the
water temperature demanded some fan assistance.

"Remco" <whybcuz (AT) yahoo (DOT) com> wrote

Thanks - I am Dutch but live in the US. Our names/models might be
totally different.
Remco

Well, that makes three of us. Ronald is an engineer as well.
I can't resist asking " how many electrical engineers does it take to
fix a Sunny? " but unfortunately can't think of a good punch line
Maybe "Two to over analyze the problem and one to do the actual work?"


Diodes to stop back EMF really don't need to be huge since it only
needs to dissipate the spike for a fraction of time. Since car fuses
are usually large (10A or lots more), one would think the diode body
would just explode because most fuses are slow blow.
You are righ,t though -- there is always a chance it withstands it:
They may have put a good size diode somewhere.

He did pull all relays, all to no avail which basically would bring one
to the same conclusion as measuring all the relays' coils would have --
unless of course the diode is external, which is what Ronald was
concerned about.
I haven't seen that in cars -- would you happen to know if that is the
case with a Sunny? He was looking for a schematic so I'm sure he'd be
interested if you have one.

Interesting experience with that fan motor. Not sure if his problem is
intermittent, but that's a very good thought.

"Remco" <whybcuz (AT) yahoo (DOT) com> schreef in bericht
news:1113941096.068801.169010 (AT) z14g2000cwz (DOT) googlegroups.com...

Well, that makes three of us. Ronald is an engineer as well.
I can't resist asking " how many electrical engineers does it take to
fix a Sunny? " but unfortunately can't think of a good punch line
Maybe "Two to over analyze the problem and one to do the actual work?"


Diodes to stop back EMF really don't need to be huge since it only
needs to dissipate the spike for a fraction of time. Since car fuses
are usually large (10A or lots more), one would think the diode body
would just explode because most fuses are slow blow.
You are righ,t though -- there is always a chance it withstands it:
They may have put a good size diode somewhere.

He did pull all relays, all to no avail which basically would bring one
to the same conclusion as measuring all the relays' coils would have --
unless of course the diode is external, which is what Ronald was
concerned about.
I haven't seen that in cars -- would you happen to know if that is the
case with a Sunny? He was looking for a schematic so I'm sure he'd be
interested if you have one.

Interesting experience with that fan motor. Not sure if his problem is
intermittent, but that's a very good thought.

============================== RW==================

First i would like to thank all the persons who replyed to my post
But after some reassonable suggestion of Remco from Connecticut
and working all day in the pooring rain i finally have my light back.
The strange thing i found was that my radio worked fine but there was
a power leak from the radio light to my amplifier.
So i ripped the radio and the amplifier from my car and placed another one
instead, so that i can meassure the radiosystem on my workbench
There are 2 possible faults in this 1: the amplifier leaks to the minus of
the speaker
or 2: the radio has a leak from the backup cq light connection to the output
to amplifier.
This i will find out later. for now i am lighted again and can drive.

For the subject can a diode shorten during the Back EMF of a relay.
I can inform that in my job carreer i found this fault in many Broadcast VCR
and it is
sure possible altough you would think that the pulse is to short to make
this happen
but it really can be done. it is not the power that makes it possible but
the willing of
the coil to keep supply on itself.

For Remco : ik vind je grap geweldig, jammer dat je bent weggelopen
Hadden we misschien nog kat en muis kunnen spelen met rcd
Ik was vroeger ook schuldig aan dit spel.
Again thanks to you all
Ronald

Hey Ronald -- glad you got it fixed or at least you can drive the car again.
All the old school pirate stations were off the air over there last time I
was over there, so who needs a car radio anyway, right??

Ja, joh - dat zou erg geinig zijn! Ook geen porum als je d'r effe bij stil
staat: twee ouwe gozers rennen van de RCD.
Tot een volgende keer.

Best regards everyone - Remco