Bad Alternator? And where are the "battery fuses"? - F150online Forums



Bad Alternator? And where are the "battery fuses"?

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  #1  
Old 03-09-2009, 04:56 PM
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Bad Alternator? And where are the "battery fuses"?

A little background story...2001 Expedition, 5.4. Went to a boxing tournament Friday night, battery light was on. Coming home from the tournament, battery light was on, edge programmer says 11.6 volts and it started dropping, by the time I got home it was down to 8.2 volts. Saturday, I replace the original Ford battery, put the new one in, battery light is still on, programmer and handheld voltmeter tested from the alternator to the chassis says 11.4 volts. Haines manual says to check the "battery fuses", 175A. Can't find these fuses, where my battery cables go to the firewall does not look like the picture in the Haines manual. I pull the battery to look behind it on the fenderwell, still can't find these fuses. I say to hell with it, I'll look at it tomorrow, put the battery back in, start the truck for the hell of it, battery light is off and programmer reads 13.6 volts! Next morning, start the truck, battery light is on, programmer reads 11.5 volts. Still cannot find these big 175A fuses. Drive the truck this morning, battery light is on, 11.4 volts, I go to pass a guy, floor it, battery light goes off, truck remains at 13.6 volts till I get to work. Leave work, battery light is on, 11.4 volts. Come home, still cannot find these *******ing fuses.

The haines manual shows a picture of the battery cables leading to a set of terminals with two big fuses and one little spade fuse. The wiring diagram shows the black and orange cable going from the alternator to this set of terminals with the fuses, then to the starter relay. Mine does not take this route. The black and orange cable goes straight from the alternator to the starter relay. I've done many, many searches and found no answer to this question of why my truck does not seem to have these fuses.

I am about to take out the alternator and go down to Advance Auto and have it tested, which I'm sure it will fail. Before I trust the guy behind the counter, can anyone tell me, in their personal opinion that they think it is for sure the alternator? And, why can I not find these fuses or does my truck not have them, and if it does not have them, why not?

Thanks to all!

Doug
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Old 03-09-2009, 05:07 PM
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Sounds like the alternator is going bad or is bad to me.
Not sure about your fuses,,did you try looking for them in your owners manual?(If ya still have one)

Phil
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Old 03-09-2009, 05:21 PM
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Or could it be a bad voltage regulator?

Phil - I did look in the owner's manual for the magical 175A fuses and nothing is listed.

Doug
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Old 03-09-2009, 05:37 PM
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Originally Posted by gothdesigner View Post
Or could it be a bad voltage regulator?

Phil - I did look in the owner's manual for the magical 175A fuses and nothing is listed.

Doug
The regulator is internal in the altenator. Sounds as if you need a new altenator.
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Old 03-09-2009, 05:41 PM
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I concur with these knowledgable folk. If the battery light is on, that means there is a power draw on your battery, because your alternator is not supplying enough anymore. I believe that your 175A fuses are located on the passenger side of the fire wall. They are big, you would not think that they are fuses unless you were told.
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Old 03-09-2009, 08:24 PM
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Sounds like the alternator is fried. DO NOT BUY a REBUILT unit...unless you like installing alternators every other week. Most do not check the final diode which controls the electric flow in one direction only- to the battery. It is a common failure of rebuilt units that the rebuilder does not replace the final diode and while it will charge the battery, it also drains it over a day or two. Buy a NAPA new or Motorcraft new, but no rebuilts.
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Old 03-09-2009, 10:15 PM
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or make sure you get the ont with the 5 year warrenty. i had to replace mine after about a year cuz the berrings went bad like my first.
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Old 03-10-2009, 03:07 PM
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Thanks to all for advice!

Took the alternator in, had it tested, it failed. Big surprise, not really. I wanted to know what their diagnostic computer gives for a reading but the guy showed me the reading and it doesn't give any numbers, it just says "FAILED".

Wish I would've read the last two posts before I bought one! I normally only buy Ford parts and get my work done at the dealership, but this was an easy job to do myself, I'm a total gearhead, but I'm very busy and lazy. The wife wanted me to save a little money on this trip, so I ended up getting a reman, but it has a 3 year warranty, and in 3 years I'll be getting a newer Expedition.

Put the new one in and all is good! 14.4 volts! Thanks for all the help again!

Doug
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Old 03-10-2009, 07:08 PM
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No need to worry about the 175 MEGA's on that model if it happens again. You don't have them. You have a cable link by the battery instead.

Regulators are easy to check as well. No need to get into that now - Glad you got her fixed
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Old 03-10-2009, 11:33 PM
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Yes! I'm not crazy...or stupid! I knew it!
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