Electrical Problem
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Electrical Problem
I dont have a lot of experience, but I have a 95 aerostar that from what I can tell has a grounding problem. The battery discharges if left sitting overnight. All of the dash gauges die when I turn the AC on, and the speedometer and odometer work off and on while driving.
Any ideas on where to check? Is there a list anywhere of grounding points that I can look at?
Any ideas on where to check? Is there a list anywhere of grounding points that I can look at?
Post Fiend
Joined: Apr 2005
Posts: 5,720
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From: Washington state
you've got a wiring or equipment short
pull one fuse at a time in fuse block and jumper across with a digital meter in amps position.
anything more than 100 milliamps is too much current draw, will probably be the PCM/ECU computer circuit which runs all the time even with key off in sleep standby mode to keep the memory chips alive
you may also have shorted diodes in alternator rectifier which can cause battery current drain.
measure charge voltage, must be above 14v with all electrical options off
can also be a failing weak alternator, burned field coils, burned worn brushes, cooked leaking shorted regulator
Autozone and other auto parts retailers will test alternator and battery for free, call ahead
pull one fuse at a time in fuse block and jumper across with a digital meter in amps position.
anything more than 100 milliamps is too much current draw, will probably be the PCM/ECU computer circuit which runs all the time even with key off in sleep standby mode to keep the memory chips alive
you may also have shorted diodes in alternator rectifier which can cause battery current drain.
measure charge voltage, must be above 14v with all electrical options off
can also be a failing weak alternator, burned field coils, burned worn brushes, cooked leaking shorted regulator
Autozone and other auto parts retailers will test alternator and battery for free, call ahead
Last edited by 96_4wdr; Oct 10, 2007 at 09:32 PM.
Postmaster
Joined: Sep 2003
Posts: 4,452
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From: Southern California
Hi Cwbright:
Welcome to our FTE forum
I would remove the alternator first and tape up all the exposed connections. If that stops the discharge, then we know it's the problem. At this point, I am with 96_4wdr. The alternator looks to be the most promising suspect if you are discharging that quickly.
Welcome to our FTE forum
I would remove the alternator first and tape up all the exposed connections. If that stops the discharge, then we know it's the problem. At this point, I am with 96_4wdr. The alternator looks to be the most promising suspect if you are discharging that quickly.
Elder User
Joined: Dec 2006
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From: Kitchener,Ontario,Canada
Heres what I would do. Disconnect the neg from the battery & insert a 10 amp minimum rated multimeter set to AMPS. Note the current draw, it should be way less than 1amp (probably about 500mA or less than 1/2 amp). If it shows more than 1 amp, start pulling fuses until you find the affected circuit.
Report back what you find!
Note; Do not turn on the ignition key as bad grounding can damage sensitive electrical parts of the system!
Aeroman.
P.S. Even a 1 amp load will drain a fully charged 75 AH battery in about 2-3 days if the van is not used daily!
Report back what you find!
Note; Do not turn on the ignition key as bad grounding can damage sensitive electrical parts of the system!
Aeroman.
P.S. Even a 1 amp load will drain a fully charged 75 AH battery in about 2-3 days if the van is not used daily!
Last edited by Aeroman59; Oct 13, 2007 at 06:01 PM.
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There is a body ground that connects to the inner fender wall. Open the hood. You will see it just behind the air cleaner/ignition module. temporarily remove it from the wall, clean the connection and also take some steel wool to the area where it bolts to. It might not be getting enough metal to metal contact. I removed and installed a new engine last summer in one of my aeros'. I forgot to reconnect the ground and it acted exactly the way you described your problems.
Elder User
Joined: Dec 2006
Posts: 830
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From: Kitchener,Ontario,Canada
Does the battery take charge if you put it on a battery charger? You could have a battery problem or a charging circuit problem or an electrical circuit fault. Thats why it's important to measure the key off current flow from the battery.
You can also check the battery is charging fully with a Hydrometer, also as pointed out above ,the charging voltage should be about 14-15 volts. Too low & it'll take too long to charge & to high & you'll boil your battery.
The fact that the battry goes dead overnight , does point to a circuit malfunction or an auxillery device remaining on. Do you have any non standard devices wired into the electrical system ? ( an alarm for instance).
Aeroman.
You can also check the battery is charging fully with a Hydrometer, also as pointed out above ,the charging voltage should be about 14-15 volts. Too low & it'll take too long to charge & to high & you'll boil your battery.
The fact that the battry goes dead overnight , does point to a circuit malfunction or an auxillery device remaining on. Do you have any non standard devices wired into the electrical system ? ( an alarm for instance).
Aeroman.
Last edited by Aeroman59; Oct 16, 2007 at 06:57 PM.
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Ok, a little bit of an update. I've been leaving the battery disconnected when I park the van, and it hasn't had any trouble starting. As far as I there hasnt been anything extra installled electrically. And, the speedometer and odometer have completely stopped working now - the odometer wont display anything, the speedometer just stays at 0.
Thanks for the replies, I'm going to try and track down the problem when I get some time this weekend.
Thanks for the replies, I'm going to try and track down the problem when I get some time this weekend.
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Post Fiend
Joined: Apr 2005
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From: Washington state
check circuit fed by fuse #17, feeds instrument cluster
loose or failed PSOM module on instrument cluster circuit board, fairly common failure in Aerostars.
search aero forum for PSOM for more info
loose or failed PSOM module on instrument cluster circuit board, fairly common failure in Aerostars.
search aero forum for PSOM for more info
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