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searched around couldn't really find anything on this problem... a couple friends and i were messing around in the garage i was replacing the battery in the tour..took it out set the old one on the ground and then had to take a dookie so i left the idiots alone in the garage they thought they would help by going ahead and throwing the yellow top in there..but they hooked they had the wires crossed and hooked the ground up to positve and positive to ground the horn starts to sound.....so they unhook it but i put it all back together and my battery light is on and the alternator is definately not charging the battery..i know on the 2.0 there is a megafuse inline..is there one on the 2.5 if not is there any thing else they could have screwed up there...
thanks in advance
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Did that to my neighbor's Buick Park Avenue... Although I think it had reverse protection, horn did sound, but alt continued to work normally, along with rest of car... check the fuses in the power distribution box... I am not sure... maybe you did [censored] the alt over, considering on most cars its a direct cable, not sure how the Contour has it...
Former owner of a 1995 Ford Contour GL w/ 2.0L ATX
Proud owner of a 2005 Ford Taurus SE 3.0L V6 Vulcan 
--Looking for Commodore stuff (Drives, Units, Amiga, games, etc)If anyone has any of this laying around and wants it gone, lemme know --
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megafuse is located BEHIND the engine, between the firewall and the UIM. Find your coilpack(spark plug wires all lead to it) and look underneath it.. you'll see a black, plastic rectangle housing that holds some wires for the wire harness. Secured to the BACKSIDE of this wiring harness holder(between the firewall and the holder) is the megafuse. Best way to check it: don't remove it to check it. - You'll need a multimeter.
- Remove the six spark plugs (not which ones they go to first.. ther should be a drawing on the coilpack, in the middle of all the spark plug connections, but it MAY be worn off from heat) WRITE DOWN which cylinders the plugs ran to.. ) NOTE: remove them from the COILPACK END... not the cylinders themselves. only do this after verifying the drawing THREE OR FOUR TIMES, or drawing your own to be sure..) NEVER remove more than one spark plug from the cylinder end if not needed, as this can easily lead to the wrong ones being hooked up and running poorly, etc
- Remove the coilpack (four bolts holding it on, be sure to notice that two of them also hold on a radio noise suppresor and the coilpack ground strap.. you'll need to make sure they both get put back on..) In the pictue below the coilpack is removed, and you can see the very tip of that black plastic wiring harness holder sticking up, kind of at an angle...
- now that you are looking at the mounting points for the coilpack, you can see the wiring harness that I was talking about (long plastic rectangle that runs the length of the UIM), and you should see two small metal posts coming from the backside of it, and angled towards the firewall. Between these two posts is the megafuse.
In the image below you can see the wiring harness holder (off of one of its mounts.. you don't need to do this, though..you can also see the coilpack mounts) You can see a gray/white wire and connector secured to the top of the rectangle as well... just BEHIND this connector is the megafuse. (You can see the main wire with a red rubber wrapping around it, coming in from the alternator on the left, and then leaving to the battery from the right. To be honest, its right about where that hole is drilled and the wire is coming out (though the hole/wire has nothing to do with the megafuse, its just for locating purposes is the only reason I said it.
- You can either remove the megafuse, by removing the nuts securing the fuse (those two posts), OR by simply checking resistance between the posts.
- place the multimeter on "ohm" or "Diode-check" mode. on diode-check mode, it should beep when you touch both ends (because of almost no resistance, through the fuse) if it doesn't beep then it is likely open, because of an open fuse.) Touch both posts, or touch the actual metal bands of the fuse in the middle of the two securing posts (the fuse looks like an inline fuse to an amplifier (round, metal bands on the ends...)
- MAKE SURE that you are touching the posts completely, as mine didn't beep a couple of times in a row, and then the third try it did. You might also change to ohm mode and check for actual numbers.
GOOD FUSE = nearly 0 ohms
BAD FUSE = anything in the MEGAOHMS range, OPEN, INF., or the INFINITE symbol (like an 8 laying sideways)
looking at roughly 30 minutes, only because you've never done it, and you have to remove all the plugs on the coilpack. HTH (wow.. at 5:30am, too.. Do I have a life?no (I didn't space "no" on purpose, because I didn't even have to think about it before typing the answer) Ray
'99 CSVT - Silver #222/276
In a constant state of blow-off euphoria.
Originally posted by Kremitthefrog:
I like to wear dresses and use binoculars to watch grandmas across the street.
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thanks in that case i am sure that is what is wrong just wasn't sure if the 2.5 had that fuse as well thank u very much
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Joined: Jun 2000
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I believe your alternator is burnt up, or to be exact, the rectification bridge inside.
The rectification bridge is an integrated part inside the alternator. It consists of multiple diodes that transform the AC voltages generated by the alternator windings to DC to supply the vehicle electricals and to charge the battery. These diodes are backward biased when battery is hooked up correctly and when the engine is not operating, therefore they draw no current from the battery. But they do become FORWARD biased when battery is hooked up backwards, and form a close circuit to the battery allowing HUGE current to flow, and resulting in instant destruction of the diodes themselves due to the massive heat generated.
Lesson I learned from you experience: Never leave idiots in the garage and go taking a dookie, take it right in front of them in the garage instead if they have to stay in.
Good luck.
1997 Contour Sport Duratec MTX
2000 Olds Intrigue GLS Sterling Edition
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Except for the fact that there is a mega-fuse inline with the alternator to prevent that from happening. SHOULD not be any reason to burn up the alternator.. your description is POSSIBLE, but the fuse SHOULD have prevented this.
At any rate.. 20 minutes, possibly to check the fuse and replace.. or 1-6 hours depending on severity of bolts, etc, on the ALT to replace, simply on a whim?
the smarter choice would be to at least CHECK the fuse before ripping in to a repair such as this..
Ray
'99 CSVT - Silver #222/276
In a constant state of blow-off euphoria.
Originally posted by Kremitthefrog:
I like to wear dresses and use binoculars to watch grandmas across the street.
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Joined: Jul 2001
Posts: 7,100
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Except for the fact that there is a mega-fuse inline with the alternator to prevent that from happening. SHOULD not be any reason to burn up the alternator..
At any rate.. 20 minutes, possibly to check the fuse and replace.. or 1-6 hours depending on severity of bolts, etc, on the ALT to replace, simply on a whim?
the smarter choice would be to at least CHECK the fuse before ripping in to a repair such as this..
Oh.. and a Bridge rectifier (you are referring to) to create AC would have TWO placed in a REVERSE-biased manner, and two in a forward-biased manner..
Normal operation would pass the positive portion of each AC waveform through to the battery and car as positive voltage, and the negative portion to either ground or a discharge cap.
reverse hookup would then send the negative waveforms to the same exact setup, and would be reverse-biased, allowing NO CURRENT flow to the battery (but MAX flow through the now forward biased other pair to the discharge cap/ground. causing the fuse to blow.
OR to paraphrase: your megafuse is likely STILL the culprit.
Ray
'99 CSVT - Silver #222/276
In a constant state of blow-off euphoria.
Originally posted by Kremitthefrog:
I like to wear dresses and use binoculars to watch grandmas across the street.
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Joined: Jun 2000
Posts: 56
CEG\'er
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CEG\'er
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Originally posted by Ray:
Except for the fact that there is a mega-fuse inline with the alternator to prevent that from happening. SHOULD not be any reason to burn up the alternator..
At any rate.. 20 minutes, possibly to check the fuse and replace.. or 1-6 hours depending on severity of bolts, etc, on the ALT to replace, simply on a whim?
the smarter choice would be to at least CHECK the fuse before ripping in to a repair such as this..
Oh.. and a Bridge rectifier (you are referring to) to create AC would have TWO placed in a REVERSE-biased manner, and two in a forward-biased manner..
Normal operation would pass the positive portion of each AC waveform through to the battery and car as positive voltage, and the negative portion to either ground or a discharge cap.
reverse hookup would then send the negative waveforms to the same exact setup, and would be reverse-biased, allowing NO CURRENT flow to the battery (but MAX flow through the now forward biased other pair to the discharge cap/ground. causing the fuse to blow.
OR to paraphrase: your megafuse is likely STILL the culprit.
Ray
I really hope there is a fuse in the +12V link between the alternator and the battery that protects. But at least the schematic of the charging system in my repair manual shows none.
I'm not understanding your description about the way a rectifier bridge works and how that would prevent a backward-connected battery from frying up the diodes. Below is a link to a simple schematic of the rectifier circuit I sketched. If you reverse the battery connection you should expecting a huge current. I wish I'm wrong though.
The smoothing capacitor alone at the alternator output is too small in capacity to blow any fuse in our cars, even the lowest rating ones (3A), on a 12V battery.
charging
1997 Contour Sport Duratec MTX
2000 Olds Intrigue GLS Sterling Edition
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