alternator issues
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Senior User
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alternator issues
A friend of mine has a 91 f150 302, I put a new 40 amp alternator on it and one new plug ( 2 black wires with orange stripes and white wire with black stripe) i am replacing the second plug tomorrow but i cant identify a green wire that attaches to the solenoid has an inline fuse in it. Anyone have any idea what it is. Volt meter reads about 12V but the battery light is still on. Im going to replace the burned green wire see what happens. Thanks for any help anyone can provide.
Fleet Mechanic
Joined: Jul 2006
Posts: 1,346
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From: Rapid City, SoDak
Originally Posted by donsboy
A friend of mine has a 91 f150 302, I put a new 40 amp alternator on it
Fleet Owner
Joined: Aug 2005
Posts: 23,668
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From: Easton,Ks
I take it you are talking about the starter solenoid, it sounds like the green wire is a power pickup for something somebody added for something. You should be able to follow it to where it goes.
40 does sound too low for your truck, get at least a 65 Amp.
Here is diagram of your charging system.
40 does sound too low for your truck, get at least a 65 Amp.
Here is diagram of your charging system.
Senior User
Joined: Oct 2004
Posts: 371
Likes: 1
From: Wetaskiwin, Alberta
The green/red stripe wire is standard Ford power wire that runs to the alternator. You cannot run without this wire as it will trigger your red battery light on the dash. You also cannot "tap" into this wire to use as a power supply for anything else as any drop in voltage on this wire will trigger your battery light. I know this from experience because I tried to use this wire as the ignition power line for my electric fans. The battery light went out as soon as I removed my splice and went to a different ignition power supply for the fans. 40 Amps is waaaaay too low for the truck. You need at least 65 Amps. I am running a 3g Amp at 130 amps.
Cheers!
Mike
Cheers!
Mike
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
check out www.fordfuelinjection.com has 3g alts with premade wiring harness's for great prices and will be a great upgrade to your 40amp altenator :-)
