Question for you fine gentlemen and ladies

Today my 'tour took me through another kind of adventure.

I'm going on 120 on the highway and notice it was responding slower then usual. Regardless, I keep driving, and all of the sudden baaaam, it dies right in the middle of the road. I sit, wait, crank, no go...crank again and off I go again.


Right about now I notice that the throttle is slower than before and the tractor on the right lane was picking up speed faster than me, hell the driver was happy that he wasn't the one jamming the traffic.

All my lights were dead and so was my radio, but the no lights factor was scarry due that this happened 1/2 hour ago, it's almost dark here. I also noticed that the turn signal would come on 1/2 time slower then regular.

IT'S NOW that i notice the battery lighting half dimmed when I floor the car or use the brakes and sometimes at idle.

Anyways, I finally get closer to home( off the highway) and notice the throttle response from a complete stop being slow to the point of embarrassment. I pull into a parking lot, kill the engine and started scratching my head for solutions. At this point the flashers would not work and the car would not start. The starter would make the "dead battery" noise and all the colors of the dashboard were on.

I get a boost from another car and wait. Throttle response when in drive or reverse was slow, but when I tossed it in Neutral, the engine would rev normally. I wait 5 minutes and drive home with 1 horse power and almost no throttle.

Car doesn't start anymore once in the driveway and I'm both pissed and worried because tomorrow my day is full of meetings one farther apart than the other.

My bet is the alternator is well on it's way out, I'm glad that at least it got me home safe.

what's your diagnostic?

ninja edit: I managed to start it again, as the battery is good and the alternator puts out 7V; it's done.

alex894 said:

... I managed to start it again, as the battery is good and the alternator puts out 7V; it's done.

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Yep, alternator is done. Of course, being a Zetec, it is easy to change it out. Look for the battery going to after putting in a new alternator. Chances are the battery also took a beating with the bad alternator.

What do you mean "puts out" 7V? Did you somehow test the output of the alternator without the battery in the circuit? (which is incredibly dangerous, btw)

If you had a full circuit then the voltage you are seeing is the voltage in the system, either:
a DEAD battery (ie.. 7v) and NO output of the alternator
a good battery, but something drawing it down to 7V (bad thing!)
a good alternator but a bad battery and a bad megafuse, etc keeping your alt from charging the battery.

Either way, I think you should do a couple things before being sure..

first, you MUST start with a FULLY charged battery, either trickle charge yours of swap in a known charged one.

Now:
measure the voltage at the battery terminals.. should be 12.0VDC or higher.. if not, start over with the charging/good battery replacement.

Start the car, and measure at the battery again.
13.2, 13.8.. 14.2?? okay its charging.. shouldn't be more than about 14.2 or 14.4 ish.
If its LESS then your alt is likely out, you have a bad megafuse, or bad wiring (grounds) from the alternator to the chassis, the battery to the chassis, etc.
If its more then your voltage regulator (built in the alt) is likely bad.

Turn on the headlights, turn off the car. wait 60 seconds.
Measure the battery again.
12.0VDC or higher.. if not, bad battery.

There you go.. let us know what you find.

i belive is the alternator, i would put a new battery too

Ray said:

What do you mean "puts out" 7V? Did you somehow test the output of the alternator without the battery in the circuit? (which is incredibly dangerous, btw)

If you had a full circuit then the voltage you are seeing is the voltage in the system, either:
a DEAD battery (ie.. 7v) and NO output of the alternator
a good battery, but something drawing it down to 7V (bad thing!)
a good alternator but a bad battery and a bad megafuse, etc keeping your alt from charging the battery.

Either way, I think you should do a couple things before being sure..

first, you MUST start with a FULLY charged battery, either trickle charge yours of swap in a known charged one.

Now:
measure the voltage at the battery terminals.. should be 12.0VDC or higher.. if not, start over with the charging/good battery replacement.

Start the car, and measure at the battery again.
13.2, 13.8.. 14.2?? okay its charging.. shouldn't be more than about 14.2 or 14.4 ish.
If its LESS then your alt is likely out, you have a bad megafuse, or bad wiring (grounds) from the alternator to the chassis, the battery to the chassis, etc.
If its more then your voltage regulator (built in the alt) is likely bad.

Turn on the headlights, turn off the car. wait 60 seconds.
Measure the battery again.
12.0VDC or higher.. if not, bad battery.

There you go.. let us know what you find.

Click to expand...

Thanks for the replies guys,

Ray, It's 7 v constant for a minute and than drops.... I measured the batery terminals. I have no "known good" battery at the moment, I'll leave that for tomorrow.

If I turn the headlights on while the car is running, the engine dies.

If I leave the car alone for 15 minutes, the car fires right back up, but will not if I shut it down and try again immediately.

Where is the megafuse located?

edit: I read here that it's certain the megafuse is gone only is the battery light stays on constantly. Mine is dimmed on braking and sudden acceleration and flickers 90% when that happens.

On the firewall, against the rear of the engine bay.. its "under" the coilpack in a small plastic black rectangle. the main wiring harness and wires run along there and you should see two metal posts that stick up from the box, once you pop open (or break off as most do, lol) the lid.

Ohm that out, should be near shorted, after all its a fuse.. if its HIGH resistance, or infinite, then your mega fuse is bad.

Your car is running on 7V.. that's not even CLOSE to enough, so when you toss the lights on, it dies, surely.

You really MUST have a charged or good battery to start with, though.. you can't ever say what the problem is.. the alternator's output will vary based on the charge on the battery, etc, so you can't say "oh.. not putting out enough voltage from the alt!" because a dead battery will change that amount anyway..

edit: check out the UIM/LIM removal how-to (Duratec maintenance forum) for some pics of the engine bay and you can see the megafuse box in a couple of them.

edit, edit: you have a zetec.. dang it, I suck at comprehension tonight.. I have no idea where it is on a Zetec (or if there is one, though I suspect there must be!)

I found it.....the megafuse is right near the throttle body behind the engine, clips in right on the intake manifold. I tested it and it's fine. I test the outside connectors on each side of the fuse

The battery measured 11v and incremented by .05 to 12 when I was done( with car off after my attempt to start it). Car won't start anymore....maybe because it's getting colder outside and recharge is weak.

now ....how do I test the ground wire. Between the (-) terminal and the car's chassis and I get nothing on the tester

edit: could adding a remote lock/start system have anything to do with this? for 2 weeks or so I didn't have any problems, and I can't think that there would be the possibility of the remote system drawing power because it's impossible and the warning LED does not draw that much power to bring drain the battery.

Next on my list was upgrading the "projector fogs" to real projectors, I guess I'll put that on hold for a bit until I figure out the power draw/shortage

you tested from the BATTERY negative to ANYWHERE on the chassis, and you should be in "resistance" mode.. if you are in voltage mode then you won't see anything.

the meter measures the DIFFERENCE from lead to lead, and from negative to chassis they are the SAME so you get a 0V difference, (ie, the meter reads 0v)

you should OHM the wire and get a near short, the same way you test the fuse.

you should also test from the alternator ground to chassis..

and then lastly inspect the alt POS. from the alt to the megafuse to the battery.

after all that, you have bad battery or a bad alt, but you need that good battery to know for sure on those two.

I did OHM it......and

alternator to fuse ...ok
alternator to battery ...ok
fuse to battery ...ok
fuse ...ok
battery to chassis ......nothing
alternator to chassis....nothing

edit:where does the battery/starter ground to the chassis?

alex894 said:

I'm going on 120 on the highway

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LOL, I read this and was wondering why the mods left it, then I saw that you were from Canada :laugh:

BoSoxBruin said:

LOL, I read this and was wondering why the mods left it, then I saw that you were from Canada :laugh:

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lol, I was wondering the same thing since a tractor was racing me and won by a split second.


OK Guys, before I left for work, I charged the battery for 10 minutes and did some measuring.

Now, alt to chassis was OHM and so was battery to chassis.

Battery when the car runs...I measured 12V, battery with car running, lights on, 12 V constant.

Alternator produces 14v today:shrug:, oscillating from 10-14V measured positive on alt to chassis...motor running.

The alternator should not be oscillating that much or that widely.

It should be a fairly steady (within .2 or .3 volts) output, whatever it is putting out.

If you are saying that at the ALT you are seeing 10-14V and at the battery (during the same period) you are seeing 12V constant, then I'd imagine you have a missing or broken wire between the two (ground or positive, though you ohmed out the positive wire...)

However, I'd also suspect the alternator as being faulty with that kind of a sweeping output, or times with no output.

If your car is driveable, are there any auto shops or parts stores that will test the alternator for free? The US has Autozone or Advance, etc and they will test the alt/battery for free and they can even do an "in car" test, though not as thorough, though with the condition of your alternator I would suspect it wouldn't take a thorough load test to prove or disprove its condition.

Thanks Ray.

Now they say there are 2 types of alternators for these cars, 15A and 30A.

If mine is a 15 (assuming) can I put a 30A because I plan to do a sound system and projectors on fogs&headlights? How safe would a 30A be instead of a 15A? and is it really necessary to step it up to 30A (if I have a 15A) with my to do list?

I just had this EXACT same thing happen to me this past winter in my Taurus. Did not make it home though....had to get a a cab home at 1am in sub-freezing temps. I had two places tell me my alt. was just fine! Heck, one of them was even the guy who does all of our local P.D. cars. Not so, I ended up wasting money on a repair I could have easily done myself in a couple of hours. If your mega-fuse is fine, just replace the alternator and enjoy your car again!


Edit: lol...I was wondering about the "120" thing too...I had resigned myself to thinking you were on some "highway 120" or something...

I`ll do further testing and investigation when I get back home, thanks for all the help guys...

Uh, the alternator is a lot higher rating than 15 or 30 amp. I'm betting around 110 or so as far as the rating.

amc49 said:

Uh, the alternator is a lot higher rating than 15 or 30 amp. I'm betting around 110 or so as far as the rating.

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yeah you're right, Today they tell me that the 2 possibilities are 108A or 130A.
I was scratching my head when they told me 15 and 30A too, how the hell was that possible when the main fuse is 175-ish or so Amps......:shrug: