Charging system light
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Joined: Oct 2007
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Charging system light
Hi,
New to this but I am aggravated! 93' Aerostar XLT charging system light comes on when RPM's above 2200. Does not come on when at idle. Thought is was the alternator, so I took it off (why does bolt have to thread in from the back? argh!!!!) and took it to the parts store to be tested and they said it was fine! Put it back on and checked all connections and still having the same problem. Any help would be much appreciated.
Thanks,
Jason
New to this but I am aggravated! 93' Aerostar XLT charging system light comes on when RPM's above 2200. Does not come on when at idle. Thought is was the alternator, so I took it off (why does bolt have to thread in from the back? argh!!!!) and took it to the parts store to be tested and they said it was fine! Put it back on and checked all connections and still having the same problem. Any help would be much appreciated.
Thanks,
Jason
Postmaster
Joined: Sep 2003
Posts: 4,452
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From: Southern California
Hi Shadowman:
Welcome to our FTE forum
Check the voltage at high RPM. The correct voltage should be around 14.5V. If you get something like 16-18V, it's too high and your alternator is bad. The testing done at the part store is extrememly unreliable.
Welcome to our FTE forum
Check the voltage at high RPM. The correct voltage should be around 14.5V. If you get something like 16-18V, it's too high and your alternator is bad. The testing done at the part store is extrememly unreliable.
Elder User
Joined: Feb 2006
Posts: 681
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From: SE Michigan
Make sure the belt tension is tight. I've had a belt slip at higher engine speeds and not know it unless the alt output went down. The belt can slip at the higher speeds and you won't hear it like you would at lower speeds like a power steering belt squeal. Try it with the belt a little extra tight and see if it helps it go away. If not it may be the alternator going bad. And like has been mentioned, the auto parts stores don't test them for longer periods of time or higher speeds or with a heavy load. So they don't always show the problem that you are having with it.
Elder User
Joined: Dec 2006
Posts: 830
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From: Kitchener,Ontario,Canada
If the alternator is good then the rectifier/voltage regulator is bad. Charging system voltage should be 14-15volts DC across the battery with engine running.. It is still possible with some of the rectifier diodes gone south to be charging ,but at less than full wave operation. This means that your battery might not go flat but it does no good & charging current is reduced.
Is the rectifier integrated with this Alternator, sometimes it comes with the Alternator & is not sold seperate?
Is the rectifier integrated with this Alternator, sometimes it comes with the Alternator & is not sold seperate?
Elder User
Joined: Dec 2004
Posts: 718
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From: North Jersey, New Jersey
Originally Posted by Aeroman59
Is the rectifier integrated with this Alternator, sometimes it comes with the Alternator & is not sold seperate?
http://www.rockauto.com/catalog/raframecatalog.php?catalog=48&partnum=GR784B&a=FR4 8-GR784B
Looks like you'll need a hex driver to get the screws holding it on the alt off.
Last edited by krankshaft; Oct 31, 2007 at 06:14 PM.
