FUSES - Is the Manual incorrect?

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Nightcheck - 04 Aug 2006 19:24 GMT

Hi -

I have a 1987 Fiero GT and while changing a fuse (for the coolant fan
relay coil) - I noticed something very odd.

In my owners manual (Yep - I'm the original owner) - in Section 6.8
it has a diagram showing the layout and to the side designates which
fuses (by color and amp) go where.
Incidentally, besides in the manual - if you wipe away the grime by the
fuses - it also tells you the proper amp to go in each category.

Well - lo and behold - as I removed some of the grime where the fuses
are - I noticed the last fuse (#17) very clearly said 25 Amp CTSV-Lid.
(which is for the rear compartment lid release and light, power door
locks relay and power sport mirrors control) - YET the Manual says
it should be a 20 Amp (which was the one being used)

My question is - which do you think is correct - and can using the
incorrect one cause problems. If the manual is correct (20 Amps which
is what was being used) - then no problem.
However, if the Fuse Box data is correct (and the manual incorrect) and
it should be 25 Amps - that would mean I am and have been supplying 25%
less amps. If I put in a 25 Amp fuse assuming the Fuse Box is correct
and the manual is incorrect - if that turns out to be wrong - then I
would be supplying 25% too much.

Which is worse - too much - too little - or 25% difference wouldn't
matter?

Thanks for any insight anyone has on this..
Rick

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John Craker - 05 Aug 2006 00:51 GMT

Usually - go with what the fuse panel says.
The manuals are written by people - and people make mistakes!
I've found several errors in the factory manuals, and the owners book is no
different.

Besides that....
You're not supplying more or less power to the circuit. You're just letting
more or less current flow before the fuse blows.
5 amps is nothing anyhow.
If it was a toss up between "do I stick the 5 amp or the 25 amp one in" -
well yeah, it's time for research. 20 or 25 you'd never notice!

> My question is - which do you think is correct - and can using the
> incorrect one cause problems. If the manual is correct (20 Amps which
[quoted text clipped - 7 lines]
> Which is worse - too much - too little - or 25% difference wouldn't
> matter?

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Boomtastic Racing - 06 Aug 2006 16:02 GMT

>Hi -
>
[quoted text clipped - 27 lines]
>Thanks for any insight anyone has on this..
> Rick

Rick,

I'd run with the same value that was printed on the fuse box.
Production line changes happen faster than the service/owners manual
can keep up with.

I understand your thinking regarding delivering less amperage, but
unless the fuse was blown then it never called for more than the value
of the fuse. In other words, if it needed 25A and you only had a 20A
fuse - which was not blown - then you never exceeded a draw of 20A,
let alone a full 25A. (This is simplifying the fact that the amounts
are at which the fuse blows, not the total amount of current it can
withstand.)

Fuses are put in place to protect both the wiring and the device(s)
connected to it. Using the wrong amperage fuse can lead to problems,
but conditions much be right. For instance, if you replaced a 5A fuse
with a 25A fuse, things would probably be fine UNTIL whatever was on
the other end of the circuit started called for more amperage (which
usually happens during a short). At that point the wiring, which is
guaged for the 5A draw, would start to heat and melt the covering. The
fuse would keep supplying current until it reached the max it could
handle, then it would give out.

Btw - "grime" on the fusebox?? Usually that's a clean area of the car
.. :)

Eric

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labtech1 - 09 Aug 2006 02:43 GMT

My self, I'd stick the 20 amp in and if it causes no problems ( blowing
frequently) I'd leave it. Better to have a fuse blow out then a wire burn or
melt, by having a too high an amp fuse in. Remember, electricity, will burn
or blow out the weakest link if there is a short .... be that a wire, or
fuse. If you have frequent blow outs of the fuse, replace it with the 25
.... Like someone said a five amp difference you'll never really
notice.

> >Hi -
> >
[quoted text clipped - 56 lines]
>
> Eric

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