I have a 2000 Focus SE (Manufactured 11/1999) with the 2.0L Z-Tech
engine, A/C, A/T, P/S, P/L, P/W.
Here's the problem:
When driving down the road, it seems that the voltage of the electrical
system dips. All lights go dim, and the blower motor slows down. It
does this for about 5-seconds then returns to normal. The problem keeps
repeating itself. It seems to do it more when it's warm outside or
there's a heavy load on the electrical system.
With lights on, rear defroster on, radio on, blower on 4, and windshield
wipers on continuous low, and 10-15 miles of freeway driving it will
start acting up. However, with just lights, radio, blower on 2, and
wipers on 3 or 4 intermittent, it seems to take 35+ miles of highway
driving before symptoms appear, if at all.
The other thing is that when starts to really act up, the radio will
crash (like a computer) and I have to reset it.
To me, this seems to be a problem with the alternator. It was recently
replaced due to bearing wear by the mechanic shop. And does anybody
know what the specified output of the alternator is? I've seen 105 amp
and 110 amp.
Rather than ask us, why not take the care back to the mechanic?
It sounds like it could be the voltage regulator, which is usually part
of the alternator or a problem the electronics in the alternator.
Did you take it with lights on, rear defroster on, radio on, blower on
4, and windshield wipers on continuous low, and 10-15 miles of freeway
driving it will start acting up. However, with just lights, radio,
blower on 2, and wipers on 3 or 4 intermittent, after 44 miles of
That might be the only way to duplicate the problem. Of course, you need
to have the mechanic set up with the meters and all, so that she can
just put them on as soon as you pull up to the shop.
And, what happens when you drive the car for more than 50 miles without
all the electric stuff on?
Also, do the light dim, motors slow down, etc., more than if you shut
off the engine? I am wondering if there is something that is shorting
out, causing a big drain on the system. If the voltage drops low enough
to reset your clock, it sounds more than what would happen than if just
the alternator stops making electricity.
If you're going to reproduce the problem, that might be the only way.
I am also wondering if you can get any info out of the OBD II. You are
also able to hook up an iPhone or iPod touch to the OBD II, but you need
special cables and devices (I think starting at about $100). This may
At about the time of 1/6/2010 6:09 PM, dr_jeff stated the following:
Well, after 20 miles of driving. Something else that I mentioned though
in another post has me wondering. It only seems to act up when the
vehicle is moving, more so over bumpy roads. That tells me it's a
connection problem somewhere. Could be a cold-solder joint in the
voltage regulator too, that would explain BOTH the voltage cutout AND
the fact that it only really happens while moving. I just recently made
this connection myself.
It rarely acts up until I stop for a few minutes then start moving again.
It doesn't reset the clock on the raido. What I was referring to was
that the CD player in the radio will crash. The radio itself works
fine. I have to remove the faceplate for a few seconds and then put it
back to get the CD player to work again while I'm on the road.
They already tried that. No codes were stored in the computer.
The thing that gets me though, is that this didn't start happening until
AFTER the alternator was replaced. The original one was replaced due to
the bearings going out. I really want to put some hurt on the engineer
who designed this thing though. Who in their right mind would place the
alternator between the engine and the firewall where you have to
dismantle the top half of the engine compartment to get to it?
At about the time of 12/31/2009 10:12 AM, David Skelton stated the
I wonder if the alternator was replaced with a lower-capacity unit. It
seems to me to be a design flaw if the alternator cannot output enough
power to run all those loads on your focus. When I'm driving home, I
run the engine between 2500 and 3000 rpm so the alternator is turning
plenty fast enough. Something else that I noticed though...it only
seems to act up when the vehicle is moving, not stopped, and it seems to
act up more on bumpy roads. That tells me loose connection somewhere.
What do you think?
On Thu, 07 Jan 2010 04:55:58 -0800, Maelstorm wrote:
It's designed to do that to speed up screen defrosting; it's pretty
standard on many cars with A/C.
WRT your alternator problem; did it have the problem before the
alternator was replaced? If not, surely the alternator or the connections
to it have to be the cause?
I've put on "brand new" reconditioned alternators on other cars, only to
find out they were no good. I would bet there is a 50% chance the
replacement here was no good. The other 50% chance is the high amp
connection to the alternator. It may have corrosion. I had a Ford Mustang
and there was recall to replace that connector. Due to corrosion it was
developing high resistance, voltage drops and heat, causing fires. I had
that car a long time, so I replaced the alternator a couple of times. By
then, even the rebuilders were including a new connector with each
There are some diagnostics on the dash
the above also works on my 2001 UK Focus
The above gives instructions for using the diagnostics whilst driving
(for a digital tachometer) but by selecting the voltage setting I assume
that you will be able to the same monitoring the battery voltage. You
may be able to see if the voltage falls gradually or just "dives over
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