Ford Truck- Now the Alternator

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Nov 4, 2012
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So I got the emergency brake mess all sorted and now functioning properly. Sure enough, I had the e brake cables reversed at the equalizer. So I took the truck for a little drive and brought it back home, and shut it off in the driveway. I went to move it later that day, and the battery was dead. So I jumped it, and it started up, ran for a little, then began to idles rough and eventually stall. The battery had died again.

So I was thinking the alternator might be bad. So I removed the alternator, took it to a local starter/generator shop, and they tested it. He said it was charging within spec, but when he opened the case there was a ton of corrosion and crap inside from sitting. So I had them do a refresh on it. They replaced the brushes, installed new bearings, and cleaned the slip rings on a lathe, and then cleaned it up and painted it. I went home and installed it, and I even took the battery back and exchanged it for a brand-new one just to be sure it wasn't the problem.

Now the truck starts and runs, but the voltage is only reading 12.25 when the truck is running, which is still way low, and the battery warning light is on.

I'm not very savvy with electrical, but I'm guessing bad cables? Maybe someone who is has a better idea?
 

pontiacgp

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Mar 31, 2006
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Kitchener, Ontario
So I got the emergency brake mess all sorted and now functioning properly. Sure enough, I had the e brake cables reversed at the equalizer. So I took the truck for a little drive and brought it back home, and shut it off in the driveway. I went to move it later that day, and the battery was dead. So I jumped it, and it started up, ran for a little, then began to idles rough and eventually stall. The battery had died again.

So I was thinking the alternator might be bad. So I removed the alternator, took it to a local starter/generator shop, and they tested it. He said it was charging within spec, but when he opened the case there was a ton of corrosion and crap inside from sitting. So I had them do a refresh on it. They replaced the brushes, installed new bearings, and cleaned the slip rings on a lathe, and then cleaned it up and painted it. I went home and installed it, and I even took the battery back and exchanged it for a brand-new one just to be sure it wasn't the problem.

Now the truck starts and runs, but the voltage is only reading 12.25 when the truck is running, which is still way low, and the battery warning light is on.

I'm not very savvy with electrical, but I'm guessing bad cables? Maybe someone who is has a better idea?
 

pontiacgp

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Mar 31, 2006
29,270
20,391
113
Kitchener, Ontario
You probably had the brake cable on right but Ford designed it backwards.....:D

for the alternator does it have an exterior regulator?.
 

axisg

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I wouldn't put all my faith in the voltage gauge, get s voltmeter on there to see whats going on.
Yes, start with cleaning all the battery connections. The lugs on the starter & solenoid are often overlooked. As well as the grounds to the body, & alternator case. Can you swap out the battery for a known good unit as a bad cell ( even when new ) can pull down an alternator ?

IIRC the Fjord uses an external Module on either the fender or was it on the firewall ?? which ties the power both in to the gauge and feeds power back to the battery. I recall many years ago I would keep a couple of those " known good " modules and solenoids in my old E150 workvan as they liked to fail pretty much without warning
 
Nov 4, 2012
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You probably had the brake cable on right but Ford designed it backwards.....:D

for the alternator does it have an exterior regulator?.

Lol Ford does some Back-asswards stuff :mrgreen:, not as much as Chrysler though. The alternator does have an external regulator.

I wouldn't put all my faith in the voltage gauge, get s voltmeter on there to see whats going on.
Yes, start with cleaning all the battery connections. The lugs on the starter & solenoid are often overlooked. As well as the grounds to the body, & alternator case. Can you swap out the battery for a known good unit as a bad cell ( even when new ) can pull down an alternator ?

IIRC the Fjord uses an external Module on either the fender or was it on the firewall ?? which ties the power both in to the gauge and feeds power back to the battery. I recall many years ago I would keep a couple of those " known good " modules and solenoids in my old E150 workvan as they liked to fail pretty much without warning

I took the battery back to Walmart and told them I suspected that it had a bad cell, they swapped it out with a brand new one, no questions asked. That was today (12/6/17).

As for the thing on the fender, are you talking about the big 3 prong remote relay/selenoid?

Also the 12.25 reading was from a DVOM, not the gauge.
 
Last edited:
Nov 4, 2012
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I think I may have figured it out...

I hooked the + wire out of the alternator to a body ground instead of the ignition selenoid right next to it. Easy fix, oops on my part.
 
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axisg

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x2 ^^ its been a while.... but I have many cold cold dark memories during Calgary winters when that damn van would not start or charge or both that have burned that particular system into my mind LOL

Thinking out loud here. The regulator tells the alternator when to charge and when to idle. So the regulator ( sensing a voltage drop from your battery via the lug on the solenoid ) excites the alternator to start charging. If it's defective it may only send a part charge, or no charge or overcharge the damn battery.

Should be 2 wires off the back of the alternator.
There should be a heavy wire off the back of the alternator to the solenoid, Then a thinner wire from the alternator into the regulator ( field ). Another wire out of the regulator will then tie/join back in to the heavy wire from the alternator or ( in my case ) I would bypass that joint and tie in directly at the solenoid. You should be able to jump that thinner wire at the alternator with 12v from the battery to "excite" the alternator into putting out the full 14.7 volts.

I also seem to recall the regulator needs to be grounded out to the fender ( or some other ground ) as well to work.

So test the alternator ( running ) at the lug at the back, and again at the solenoid. And if you are daring jump the lead on the back to see if it will put out a full 13.7-14.7 volts. Or just grab a known good spare regulator ( they used to be $25 new or $5 at the wreckers ), swap it out and see what happens.

Also dont do the Chev trick of pulling off the battery terminal with it running, its hard on the regulator ( learned that one the hard way too ).

The Fjord is just a different beast to work on. I actually like the fact that they break it out into 3 separate units instead of GM's all-in-one approach.
 
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axisg

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LOL your fender is now fully charged sir ..
 
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