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Discussion Starter #1
ok so heres the deal. ive thrown like a grand into this car and nothing had fixed the broblem. so the battery lite is on and what ive replaced is the alternator, the coil pack, spark plugs and wires. just did the tentioner and the serpentine belt. the guy said the alternator isnt putting out enough volts to keep it charged. the car viberated when the lite is on but some times it shuts off and the car runs fine. the guy i was talking to was saying it could be some computer thing. i checked the wires and everythungs fine. but i was windering if it is a computer is it the main ecu or is there some other one. and if so where is it placed?

thanks for the help guys.
 

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get a scan tool and see whats happening , a FF member close with a xcal maybe

You wasted enough money on not needed parts to buy a xcal that more then likely would of told you your issues

Tom
 

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First never ever take it back to that guy again. Computers has nothing to do with the altenator charging.

I'll bet money you have a bad ground or a exposed wire.
 

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Discussion Starter #5
no i dont think its even been replaced. but i haent found and spot in it where its messed up though. but ill ckeck again. and that guy was just a desk jocky. it was told to him from some floor guy but yeah like im sure if it was the ecu i would be having more problems then just that.
 

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You can't see it where it bolts to the starter, and it could be damaged. It's alot cheaper than replacing the ECU. Test the alternator at the alternator. Then test it at the battery. That should tell you if it's bad.
 

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First never ever take it back to that guy again. Computers has nothing to do with the altenator charging.
Actually the ECU controles the Alt charging system the regulater is built into the ECU basicly

A scan tool will tell what the alt is putting out , I have never seen a ECU go bad in the Alt section

Tom
 

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I used to teach marine EFI and the next bad ECU I see will be the first. I'm not saying it can't happen, but everytime someone had a "bad" ECU on their boat I always found a clogged fuel filter, fuel fittings sucking in air, loose or damaged connections or weatherpak plugs, altered wiring, worn out spark plugs, wrong size propellor (overloading), loose/cracked hose on the MAP sensor ... Many times the scan tool codes don't mean replace the indicated part until you troubleshoot IAW instructions. For example, lots of MAP codes were thrown due to vacuum leaks.
 

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Did you check the 3 wire plug that goes into the alternator. The wires like to pull out of the plug, and I have seen it a ton of times where the one wire pulls out, and the light is on, but it still charges. The pigtail harness to fix it is under $10.
 

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Discussion Starter #11
well when i checked the 3 wire it seemed fine i made sure none of them were coming out.
but no i havent replaced any of the battery cables. what im thinking though is running a wire from the alt to the battery keeping the one that runs from the battery to the starter. i figure that way it keeps it sharged and the other can start it. but does the other one run to anything else too?
and where does the neg run too? i know the right comes off and to a ground.
 

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I don't know enough about the Focus yet to be sure, but on some cars a wire from the alternator right to the battery would also backfeed with the engine not running (alternator volts less then the battery) and run the battery down, while possibly overheating the alternator (the fan's not spinning) and burning it out. I'll amend my bold statement above; I've never seen an ECU that died a natural death, but I've seen some that were killed by unapproved troubleshooting and inappropriate wiring modificiations.
 
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