I have a 99 Taurus with the 3.0 engine.
Today on a long trip I noticed that the battery 'idiot light' came on
under hard acceleration. Upon further investigation with a OBDII tool
while driving the vehicle I see that the battery voltage drops from a
steady 13.5V to around 12v only when the engine revs are increased to
around 4,000 or more. The idiot light comes on at these times.
This is indicative of failure of something in the charging system. Does
a knowledgeable mechanic here know if it is likely to be the voltage
regulator or the alternator? I'm not even sure if the Taurus has a
separate voltage regulator or if it's part of the alternator on this
Any advice welcome on diagnosing the faulty component.
Brushes... really. They are probably available. Can usually happen
between 125 and 190 kmiles
It ALSO COULD be the VR, but that's classic of worn brushes. But IIRC the
charging voltage SHOULD be about 14.3 to 14.6
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!
Hey thanks for your quick advice!! The car has 72K on it, low for the
year, my wife does about 8k a year.
Something always seems to 'go wrong' on these long trips. I suspect it's
because I'm the driver on long trips and she simply doesn't notice the
early warning signs.
Oh OK. I'll get the charging voltage checked independently, the ODBII
system may not be well calibrated after 7 years of operation. Will
changing the brushes help the average charging voltage also? Changing
brushes sounds cheaper than buying a new alternator, just a little more
work. I'll check online as well as ask at an auto parts store.
On Fri, 24 Mar 2006 02:52:51 GMT, Backyard Mechanic
If the car just gets knocked around town as a "wife's car" 72000 miles
can have the equivalent run time of a highway driven car with almost
200,000 on it - so I'd still say, most likely - like 90+%, brushes.
*** Free account sponsored by SecureIX.com ****** Encrypt your Internet usage with a free VPN account from
Before you buy anything, i would clean the battery cables at the
battery. check every high current power cable for corrosion and
connection torque. Check the large high current wire at the alternator
for a good connection.
How often does the car run at 4000 RPM +?.
loose belt ... under high rpm the alternator fan speeds up creating more
load maybe the belt is slipping ... otherwise its the brushes .. the
slip rings on the stator are not round or the brushes are so worn there
is not enough spring pressure and at the higher rpm the contact is not
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.