over charging alternator
Thread Starter
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Tuned
Joined: Oct 2011
Posts: 310
Likes: 25
From: Eagan, MN
I bought this carryover f150 new in July of 2017, so I am 6 months past the 36 month warranty while being slightly under the 36,000 miles. Unfortunate timing to have this trouble. The reason I have bought new vehicles the last few years is partly because of the warranty and the fact they are so complicated I don't know where to begin on fixing them. The idea is to start it up, put it in gear and go. If/when we have trouble we are at the mercy of the dealerships. A challenge with most industries for many casual observers is the use of acronyms. That's a challenge for me in this case because I have no idea what codes and numbers the mechanics are finding as we're not allowed in the shop. I know what BSM is, but not FSM or what a hall effect sensor is, or a CAN bus. The voltage numbers were around 15.5. Another forum had a post suggesting the ECU is not recognizing state of charge and the ECU may need a flash update. Someone else posted there may be a bad circuit between the alternator and the battery, code PO625. As always, your posts and suggestions are appreciated.
Grant
Grant
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Well...15.5 is telling me the Alternator is being allowed to run wide open.
That is too high to let happen too long because it's hard on Battery life and the Alternator brushes plus can shorten head light/ bulb life etc..
The Diagnostics has to be looking at the PCM control to the Alternator to see what is or is not going on.
Once this is looked at, logic should suggest where the issue is.
If the PCM is constantly signaling the charge line to the Alternator ; the Alternator will do as commanded Right or Wrong.
The Sensor at the battery is a solid state Chip system that inputs a feedback signal to the PCM on a separate line back to the PCM to tell it what it sees.
If the sensor is faulty, it may send a false signal and cause the over charge condition by proxy, as a result. Or it could be some other reason the PCM is commanding full charge rate.
Best I can do is tell you how it works, but someone has to be competent in doing the work.
Like get the Dam Scanner out and LOOK at the pulse rate and whether it ever changes or stops! Check the harness and plugup etc. Words are not going to fix the problem.
Good luck.
That is too high to let happen too long because it's hard on Battery life and the Alternator brushes plus can shorten head light/ bulb life etc..
The Diagnostics has to be looking at the PCM control to the Alternator to see what is or is not going on.
Once this is looked at, logic should suggest where the issue is.
If the PCM is constantly signaling the charge line to the Alternator ; the Alternator will do as commanded Right or Wrong.
The Sensor at the battery is a solid state Chip system that inputs a feedback signal to the PCM on a separate line back to the PCM to tell it what it sees.
If the sensor is faulty, it may send a false signal and cause the over charge condition by proxy, as a result. Or it could be some other reason the PCM is commanding full charge rate.
Best I can do is tell you how it works, but someone has to be competent in doing the work.
Like get the Dam Scanner out and LOOK at the pulse rate and whether it ever changes or stops! Check the harness and plugup etc. Words are not going to fix the problem.
Good luck.
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
The 15.5V is a indicator of low battery impedance, the BMS ( Battery Management System) is potentially recognizing the battery as below temperature and is attempting to bring it to temperature. The hall effect sensor is very visible and is on the negative terminal and easily replaced. The BMS is coming up on its max days in service so it's charge parameters will start changing. Do not rule out the battery especially if original.
Moderator
Joined: May 2005
Posts: 8,227
Likes: 1,241
From: San Antonio, TX
The OEM battery failure rate is high on these trucks. Even though you have low miles that battery could be bad. Mine died at exactly 2 years old and 24k miles. I didn’t want to leave it at a dealer for a day or 2, so I just bought a new one. 3 years and 32k miles without a single issue now. Before it died there were some symptoms, but it died fast. If you have a Motorcraft battery I would suspect that first.
Thread Starter
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Tuned
Joined: Oct 2011
Posts: 310
Likes: 25
From: Eagan, MN
My next question is regarding the battery. It has been tested, not under load or a 3 hour period, at two O'Reilly stores, an independent shop and a Ford dealer and all said the battery is good. I have been dealing with this for about two weeks, driven around 300 miles and started the pickup multiple times. Can it still be the battery as a likely problem?
Moderator
Joined: May 2005
Posts: 8,227
Likes: 1,241
From: San Antonio, TX
A new battery is cheaper than any of the other things mentioned. You need one anyway, so I don’t consider that throwing parts at it. The BMS is overcharging for a reason, and the battery is the most likely place to start.
When you get a new one, put it on a smart charger charger to get it to 100%. After you install it, let the truck sit for at least 8 hours or reset the BMS.
When you get a new one, put it on a smart charger charger to get it to 100%. After you install it, let the truck sit for at least 8 hours or reset the BMS.
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Plenty of batteries have been replaced that still started the truck. The BMS counts down days in use and eventually will stop attempting to charge a aged battery. The tester O'Reilly uses is not very efficient it mostly looks at the float charge voltage and is more beneficial for them to cut down on their own battery warranty replacements. Quick test with a voltmeter can do wonders. What is the voltage upon shut off? What is the voltage after 8hrs rest and lastly what is the voltage while cranking? If you get below 11.5v when cranking consider the battery no good. If this checks out the hall effect sensor is next and a replacement is about 22.00 from Ford.
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Thread Starter
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Tuned
Joined: Oct 2011
Posts: 310
Likes: 25
From: Eagan, MN
The Ford dealer just called and they are now convinced it is the alternator. I have virtually no faith in their ability at this point. It seems like they are throwing mud at the wall to see what sticks.
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
The defective AGM batteries arrived in 2017 and pretty much carried into late 2018 builds and into very early 2019 trucks. These batteries would test fine but fail in use. Some of these lead to a host of BMS issues and auto start stop failures. These batteries were purely junk.
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Hopefully he does, its terrible to toss money at it for no reason. The training on the BMS system from Ford was never good and lots of techs still approach these as traditional charging systems. These systems are so much more advanced and there is pages dedicated to this in the FSM and the dealership can reach out to the helpline.
Moderator
Joined: May 2005
Posts: 8,227
Likes: 1,241
From: San Antonio, TX
Everyone wonders why dealer service is so bad. The good guys leave for more pay at independent shops. If you are out of warranty never go to a dealer’s service dept. Unless they do a major amount of fleet sales because they can’t afford to lose good techs.