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nngg4
Member
This brings back bad memories. Went through this last year. 2015 Ecoboost mustang, 100% stock.
Coming up on 90k miles I proactively replaced the battery. A"platinum" East Penn mfg batter from a local ag chain. A month later charging warning lights started coming on, system deactivated messages too. Dash volt gauge constantly registered wide fluctuations and battery would drain dead, sometimes overnite. Installed a brand new motorcraft alternator. No improvement.
Dealer said battery was ok, new alt was bad, no parasitic drains. Replaced the alternator again (new motor craft). Problems persisted. Retailer replaced battery (one month old cause it was bad). Problems persisted.
I did continuity tests, drain tests. Found nothing wrong.
Took it to a third independent shop and let them keep it for a couple weeks. They went through every system and wiring and ultimately bypassed the harness from the ecm/fuse box to the alternator.
That solved the fluctuating charging and warning light problem. Finally, retailer determined the newest battery was bad even though it passed their tests and gave me another. Six months later now all is good, at least for the battery and charging system.
Now I'm replacing the clutch and hydraulics because the hydraulic throw out bearing came apart. This is another great story maybe I'll share when the repair is complete.
Note, I do not beat or race my car. It's just my daily driver. I like this car but I'd like it a lot better if wasn't have a bad run of repairs lately
Coming up on 90k miles I proactively replaced the battery. A"platinum" East Penn mfg batter from a local ag chain. A month later charging warning lights started coming on, system deactivated messages too. Dash volt gauge constantly registered wide fluctuations and battery would drain dead, sometimes overnite. Installed a brand new motorcraft alternator. No improvement.
Dealer said battery was ok, new alt was bad, no parasitic drains. Replaced the alternator again (new motor craft). Problems persisted. Retailer replaced battery (one month old cause it was bad). Problems persisted.
I did continuity tests, drain tests. Found nothing wrong.
Took it to a third independent shop and let them keep it for a couple weeks. They went through every system and wiring and ultimately bypassed the harness from the ecm/fuse box to the alternator.
That solved the fluctuating charging and warning light problem. Finally, retailer determined the newest battery was bad even though it passed their tests and gave me another. Six months later now all is good, at least for the battery and charging system.
Now I'm replacing the clutch and hydraulics because the hydraulic throw out bearing came apart. This is another great story maybe I'll share when the repair is complete.
Note, I do not beat or race my car. It's just my daily driver. I like this car but I'd like it a lot better if wasn't have a bad run of repairs lately
SheepDog
Well-Known Member
Yes, it doesn't effect the engine at all. You will get a warning light that says something like "Service charging system or battery soon"
Your voltage will stay at full alternator output, vs. the PCM trying to decide when and for how long to charge the battery. The other problem with the BMS system changing the system voltage, is for people with aftermarket fuel systems. The fuel pump output is not consistent when the voltage to the fuel pump is also constantly changing
Bullitt0819
Well-Known Member
- Joined
- Jan 15, 2019
- Threads
- 28
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- 569
- Reaction score
- 262
- Location
- Modesto, CA
- First Name
- Bob
- Vehicle(s)
- 2019 Bullitt Mustang
With five cars, two tractors and numerous powered implements I am dealing with battery issues all the time. A battery tester really comes in handy, and tells you more than either a DVM or load tester. I have a cheaper version of this one--same brand--but there's plenty to chose from.
https://www.amazon.com/gp/aw/d/B07Z67MMGC/
https://www.amazon.com/gp/aw/d/B07Z67MMGC/
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