cavalier electrics

Wonder if anyone has come across this before and can help?........ 1.7
diesel cavaliier ( isuzzu engine) starts and runs ok but as the revs climb
to around 3000 rpm the airbag warning light lights up.( as well as this my
radio facia glows a lot brighter.) I know that normally an airbag warning
light coming on is a known issue on cavs using the isuzzu engine and means
that the alternator is overcharging and i replaced the alternator 2 years
ago for the same thing. I have checked the voltage coming from the battery
with the car being revved hard and it`s 13.8 volts and doesn`t climb any
higher. I changed the charging relay in the footwell and still the same.
Does anyone have any ideas on what can or could be causing this?

 

urm.the 13.8 interests me,
sure it's not a poor earthing strap?
or the battery going toward sulphating?

how 'new' it the battery?
have you 'borrowed' & tried another?

mike

 

I cleaned the terminals and checked the wires on alternator this morning,
(sunday) i managed to open the top of each battery cell and it actually
looks like the level is slightly low. The battery terminals were clean, as
in no corrosion as i had them covered with vaseline, but i re cleaned them
with emery paper again. The battery itself was replaced when i replaced the
alternator 2 years ago as the old one was "fried"

 

quick update, the battery is maintainace free and the fluid in the cells
looks ok ( my mistake )

 

Yet another update, the 13.8 volts is ok and means that the alternator is
charging ok and not overcharging. I read a few posts on a forum ...
http://www.ilexa.co.uk/forum/index.php?board=11;action=display;threadid=337
and a guy there reported his was charging at 17.25 volts - 17.5 at 3000rpm.
(which coincides with my reading 2years ago when my alternator packed in)
i`m getting 13.8 volts at 3000 rpm. The same forum say that ....."Yikes! I
should think you've been changing a few bulbs as well lately. Anything over
14.5 on your car is bad news"

 

17.5V yikes! I saw the result - (burnt altenator. burnt wiring, fried
battery, acid everywhere) - right mess when a mates car did that.

 

<snip>
Sorry about the incomplete reply - hit the wrong key !!!
I think you need to start checking the gearbox/engine to body earthing
strap. If that is loose/broken/poor connection it can cause the same
symptom. There is also a short earthing strap on some alternators -
check that as well.
I think (it was 10 years ago!) that was the cause of the failure on my
mates old Ford Grannie.

 

i have had problems with the regulator intermittantly power surging on these
alternators, so even if you are getting 13.8 volts as you mention it may
still be faulty, the charging relay should be replaced with the alternator
as you rightly did last time.
if the regulator is playing up you will experience increased brightenss of
the lamps with engine speed, not totally sure why the airbag light may be
on, however it may be indicating a fault simply due to extra voltage through
its system.

(just an opinion based on previous experience, don't rush out and buy a new
alternator before having it physically tested)
steve.

 

check the engine earth. Check the plug onto the alternator and the next
one back for signs of corrosion. If all ok you need to check your alternator
again

 

i don't wish to pour water on this '13.8V is OK' assuption, (mainly because
things will go bang!)
no seriously, i would expect a fully charged battery, in good condition,
with a good continuois earrth around the whole engine to product about
14.5-14.8v with resonable rens.
stillsounds low to me.

check those other earth straps the other gentleman suggests.

P.S at 2 yrs i would not expect a main free bat to be faulty, but don't
count that out either.
try a spare also after doing the straps.

go from the battery neg terminal with a voltmeter and put the pos lead of it
around various 'earthed' points of the car
you should get practically no reading (potential difference).
if you do,
there's is your fault

mike

 

I just about positive that the voltage according to the new alternator guide
i got when i purchased it stated that the voltage should read between 13.5
and 14volts. It worried me at the time because even the mechanic who fitted
it said he "wasn`t sure" about it? After fitting it (2 years ago) everything
has been ok till recently, but i`ll still check the battery earth straps
when i find them and will ask about the voltage at the local vauxhall
garage. ( if they can answser that, as in my experience so far with them
they won`t offer anything over the phone and want the car in )

 

Russ
It seems quite a difficult one to sole at the moment.
I would try along the lines of "Dave Spam's" posting and check the short
strap that earths some alternators on the Cavs.
I had a Cav and it failed on mine - the symptoms started with the radio
switching itself off and the electric aerial retracting. Then various dash
warning lights started to glow some brighter/some dimmer and gradually the
main lights went dimmer.
I just wonder if the 3000rpm may be significant from an "engine vibration"
making/breaking a connection point of view?
Certainly give it a good look, I replaced mine with a battery earthing
strap - the originals were a multi-strand heavy duty wire which didn't flex
as well as the flexible mountings on the alternator and over time broke the
wire/cable.
Good luck and please keep the group posted, it's an interesting "niggling"
one!
Regards
RobO

 

Figured it at last................seems the alternator has yet again "packed
in" and only 2 year old.(it ended up shoving 17.1 volts at the battery
again....sheesh!) I managed to get a new replacement alternator under the
warranty, so fitted it last saturday, so fingers crossed and see how long
THIS one lasts!

 

Hi Russ
Many thanks for keeping us all informed. Pleased that you got it fixed and
I guess it just goes to show that you perhaps shouldn't dismiss the
simplest, most obvious fixes.
Good luck & success
RobO