charging problem 99 5.4
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charging problem 99 5.4
have a charging problem check volts at alternator and it is 11.6 volts and slowly drops over time check alt at auto zone, please help i have been chasing my tail for days.
Post Fiend
Joined: Nov 2007
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From: Somewhere In FTE Land
1 is in the fuse box under dash, 2 is in the fuse box for the engine and the 175amp is in line with the alternator
now I'm not 100% sure but check your owners Manuel on the 2 smaller fuses. I know one is under the dash and its an 10 amp.
now I'm not 100% sure but check your owners Manuel on the 2 smaller fuses. I know one is under the dash and its an 10 amp.
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still chasing
well i changed the alt plug, cause it looked ruff i cant find any fuses in my owners manuel or a service manuel, i seen no in line fuses help this has tied me up for days it has 12.2 volts when start the vehicle it goes to 11.6 i am lost please help. so i can finish my 4x2 to 4x4 conversion i have put new motor and this is stoping me from driving. thank for any info.
Post Fiend
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From: Somewhere In FTE Land
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still nothing
i check all the fuses they were not blown, i changed the plug end and still nothing, no charge at all. any other suggestions or tricks. 
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Elder User
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From: Wasilla, AK
IIRC, it is a little black fuse holder about 1 inch square inline on a heavy black wire from the alt to the starter solenoid. It also could be a fuse link that looks like a heavy wire and should have 'Fuse Link' printed on the wire. Don't take this for gospel because they changed thru the 90's.
FTE Leadership Emeritus
Joined: Sep 2000
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From: Stephensville WI
Don't over think this problem. The charging system on these trucks is pretty simple.
You have an alternator, a battery (or 2) and the wires that connect them (with fusing). If your battery is good and all the wires are good, then your problem is the alternator. I'd get it rechecked at a different shop. If you measured the voltage at the alternator output(right on the alternator) then the mega fuse probably isn't the problem. You would have been measuring voltage before the fuse, not after it.
The only other thing that could cause this is a huge current draw, in excess of the alternator's output....but if that were the case, fuses would be blowing, smoke would be coming out of the wires and you'd probably have a nasty fire on your hands.
You have an alternator, a battery (or 2) and the wires that connect them (with fusing). If your battery is good and all the wires are good, then your problem is the alternator. I'd get it rechecked at a different shop. If you measured the voltage at the alternator output(right on the alternator) then the mega fuse probably isn't the problem. You would have been measuring voltage before the fuse, not after it.
The only other thing that could cause this is a huge current draw, in excess of the alternator's output....but if that were the case, fuses would be blowing, smoke would be coming out of the wires and you'd probably have a nasty fire on your hands.
FTE Leadership Emeritus
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From: Stephensville WI
The 175 amp fuse sits between the alternator output and the load (including the battery). If you measure voltage directly at the alternator output (while the engine is running) you are measuring it BEFORE the voltage goes thru the fuse. If that fuse were blown, you would still have voltage coming from the alternator (assuming it is OK). It would just never reach the load.
An easy test to see if the 175 amp maxi fuse is OK (even if you can't find it) is to shut the truck off and measure the voltage at the alternator output. If there is voltage there (feedback voltage from the battery) the fuse is conducting electricity as designed..
Post Fiend
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From: Somewhere In FTE Land
I have replaced multiple 175amp fuses and not just on superdutys (cougar, contour, mystic, expedition and many others) while I worked at Ford. After its replacement, it never came back for that charging issue.