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On the way back from lunch today the battery light came on, also noticed a different sound (whine), when I backed up into my spot at work the battery light went off. I set my tuner to check volts was steady at 13.8 at an idle. She should make the 12 mile ride home after work and I will monitor the volts on the way home, ya know it could have waited until spring to go bad but at least it didn't strand me anywhere. Guess it's time to read up some posts on replacing the alternator, appears to be tucked in under the battery real nice, must be a remove inner fender well job by the looks of it. Time to clean the garage so I can squeeze it in out of the wind and snow. Ye ha.
I just replaced mine. I tested the alternator at the PCM harness connector pins with an ohm meter with the truck off and found a short..probally a blown diode, etc. replace the alternator and everything was fine.
you should check for loose belts, slipping belts, dead/weak batteries, poor grounds, etc..before diving into alternator replacement.
you need 14.5V in smart mode (PCM management harness connected to alternator) and 13.75V in dumb mode (PCM harness not connected to regulator).
do not connect/disconnect the PCM harness at the alternator with the engine running/key in ACC position.
The drive home started at an idle at 11.5 volts, at 75 it crept into the 13.3 range. Once back to surface streets it ran about 12.2 volts. I'll look for grounds, cables and batteries are clean as they should be, also I have myself a new whine coming from under the hood that just started at lunch, I'm betting on the alternator.
Anybody have the ford part number for a single heavy duty alternator.
The fun begins.
the stock alternator is actually the secondary alternator and is usally in the 120 - 140 amp rnge
the primary alternator is mounted at the 11:30 position on vehicles that have dual alternators and that one is 220 amps
I never found out how dual alternators are wired in terms of the PCM connection since the PCM can only control 1 alternator. I concluded that 1 alternator was connected to the PCM (smart mode) and the other not connected to the PCM (dumb mode). this would result in the secondary putting out 14.5 and the primary putting out 13.75.
I also never fond out if a 220 primary alternator can be installed in the position of the secondary alternator ..so make sure you are clear which you buy and where it mounts.
Take a look at the bottom where it says compare with similar items....the pic of “this item” does not look like it will mount in the secondary position.
Whats confusing is why in the dual alternator configuration #2 the same part number as the single alternator configuration, that means 3 different alternators for the two different set up, that's just stupid.
Morning Speakerfritz,
Still playing with the which alternator to buy debacle, last night rock auto website didn't work, this morning it is, I took some screen shots of what they list and it appears the 200 amp can be used as the 140 amps, I also have a picture of what they have for the 200 amps. I really don't need the 200 amp but it is cheaper than the 140 amp with no core charge. I know I'll probably end up just getting a stock 140 amps ( or whatever it is) just pisses me off I can't find out for sure what the deal is. LOL
New Motorcraft 140 AMP alternator installed this morning, came in through the wheel well, could have easily been an hour job but I had a few disruptions and it took me four. LOL everything turned out just fine. Started about 6 this morning, lots of coffee, some breakfast, the usual disruptions.
Might have missed it Bubba, but how old are your batteries? Type and size?
I just replaced mine with Motorcraft (that I have had very good luck with) 850 cca and everything that didn't work sprung to life.
I was getting readings as you did for a short period and I was looking at an alt. Backup cam was inop, (Blue screen) CD changer pissed away and Service brake light was on...........
Pulled the brakes, like new, dicked with the wiring to the tailgate, etc.
Fresh batts and the world came alive.
Just my story, but curious if weak batteries can bring this on. I'm at 14.3/4 while running and 12.6 at KOEO.
Might have missed it Bubba, but how old are your batteries? Type and size?
I just replaced mine with Motorcraft (that I have had very good luck with) 850 cca and everything that didn't work sprung to life.
I was getting readings as you did for a short period and I was looking at an alt. Backup cam was inop, (Blue screen) CD changer pissed away and Service brake light was on...........
Pulled the brakes, like new, dicked with the wiring to the tailgate, etc.
Fresh batts and the world came alive.
Just my story, but curious if weak batteries can bring this on. I'm at 14.3/4 while running and 12.6 at KOEO.
Denny
Batteries are 1 1/2 years old, 865cca, some of those issues you described I had when they went bad, this just happened like flipping a switch. I keep my batteries full and clean, seem to have pretty good luck with longevity.
Thanks for the two cents, little slow, must have been out looking for snow. 😃
01-09-2019, 11:32 AM
