BMS reset on 2017 GT

[Ozcraig]

Does anyone here have any knowledge to share on the BMS reset procedure following battery replacement on a 2017 model GT?

The 2017 Owner's Manual page 159 describes battery replacement but doesn't mention BMS reset.

The Mustang 2015 Service Manual calls for a BMS reset using a diagnostic scan tool after battery replacement.

Some on the forum suggest the following is successful on American market Ford vehicles:

Procedure must be carried out within 10 seconds:

1. Switch ignition on (engine off)
2. Pull and release high beam 5 times.
3. Press and release brake pedal 3 times.
4. If successful the battery light will flash 3 times within the next 15 seconds
5. BMS reset completed.

Without a Forscan reader it is not possible to determine whether the above procedure has worked and reset the battery "time in service" parameter, which is what the BMS uses to determine the best charge rate, given the age of the battery.

I imagine this procedure will work on Aussie models as the electrics are most likely the same as US models, but wondering if anyone here has confirmed this.

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[snake bite]

Sorry mate I'm going to be no help. I didn't even know anything about the BMS stuff. I replaced a battery myself about 2 yrs ago and did nothing. What's BMS do.

 

[GTP]

I just replaced my battery and performed the BMS reset procedure myself, and in front of the service manager who was both entertained and impressed.

The thing is, don't look away, because it takes a few seconds for the battery symbol to flash!

 

[PKs]

I have an 18 and have done that procedure in the past. All went as it is meant to but whether it actually did a reset is unknown. I guess the flashing of the battery light says yes.
Anyhow it has been a couple of years since and all is well.

 

[Ozcraig]

Sorry mate I'm going to be no help. I didn't even know anything about the BMS stuff. I replaced a battery myself about 2 yrs ago and did nothing. What's BMS do.

It's my understanding that the BMS (Battery Management System) uses the age of the battery to determine the correct charging profile. As the battery ages, the charging voltage may be increased due to deterioration of the battery. If the BMS does not know a new battery has been fitted it may continue to charge as if it was charging an old battery. Doing a reset tells it a new battery is in place.

 

[Ozcraig]

After doing further research I understand that export models (Euro, UK, Aus) require a diagnostic tool to perform the BMS reset. Doing the hi beam and brake light thing does not guarantee that the reset was successful even though the battery light flash happens. Apparently export models are programmed differently to US models to achieve the required emissions reductions of those markets. I don't know how much difference this makes to battery longevity, if at all. As long as charging voltage is between 13.8 -14.4V all should be ok. If the BMS thinks the battery is old it may increase the charging voltage. If it gets up to 15V that would indicate a problem.

 

[wingnutt]

That or just let it sit for 8 hours…resets itself

 

[Ozcraig]

That or just let it sit for 8 hours…resets itself

That will reset the battery State of Charge, but no the battery days in service, which is one of the parameters the BMS uses.

 

[wingnutt]

That will reset the battery State of Charge, but no the battery days in service, which is one of the parameters the BMS uses.

interesting…I have replaced my battery twice (shes 10 yers old next year)never done the reset, just plug in the battery tender and walk away

 

[Ozcraig]

interesting…I have replaced my battery twice (shes 10 yers old next year)never done the reset, just plug in the battery tender and walk away

Yep. Another one of those mystery Mustang things, like the Oil Life calculation that appears to be totally useless! I'm going to run a few days with the new battery while monitoring voltage, then do the hi beam brake light reset thing and see if it makes any difference. Not paying a Ford Stealer to do it.

 

[FrogXA]

I can confirm that this procedure worked on my 2016 Aussie Mustang. I followed the procedure, battery light flashed three times etc. Checked with Forscan on laptop 51 days later and " battery days in service" was 51 days.
I'm on my third battery now and didn't know about the reset thing when I changed out the original battery. I noticed corrosion on the positive terminal started after this and seemed to get worse and I was cleaning it more and more. I believe this was caused by incorrect charge as the Battery Monitoring System thought it was trying to charge a nine year old battery and altered charging accordingly.
Since doing the reset with the new battery a few months ago, I've checked the terminal and there is no sign of any corrosion whatsoever, so I would recommend from my experience to do this ever time you change a battery.

By the way, this can be reset with Forscan as well. I don't know what it costs now but I paid $80.00
for the extended license a few years ago and have done other tweaks like disable day time running lights, police dark mode, drivers side seat belt chime disable, door open chime disable, disable stupid double honk of horn when door open and engine running and best of all enabling Line Lock function. I even fixed a niggling problem on my BF XR8 falcon.

Well worth the money and it will keep you away from the dealership.

 

[Ozcraig]

I can confirm that this procedure worked on my 2016 Aussie Mustang. I followed the procedure, battery light flashed three times etc. Checked with Forscan on laptop 51 days later and " battery days in service" was 51 days.
I'm on my third battery now and didn't know about the reset thing when I changed out the original battery. I noticed corrosion on the positive terminal started after this and seemed to get worse and I was cleaning it more and more. I believe this was caused by incorrect charge as the Battery Monitoring System thought it was trying to charge a nine year old battery and altered charging accordingly.
Since doing the reset with the new battery a few months ago, I've checked the terminal and there is no sign of any corrosion whatsoever, so I would recommend from my experience to do this ever time you change a battery.

By the way, this can be reset with Forscan as well. I don't know what it costs now but I paid $80.00
for the extended license a few years ago and have done other tweaks like disable day time running lights, police dark mode, drivers side seat belt chime disable, door open chime disable, disable stupid double honk of horn when door open and engine running and best of all enabling Line Lock function. I even fixed a niggling problem on my BF XR8 falcon.

Well worth the money and it will keep you away from the dealership.

Thanks for that info FrogXA! I'm also now on my 3rd battery and didn't do the reset last time. I don't want to let the car think it now has an 8year old battery, hence my wish to try the reset this time.
I wont be able to confirm whether it works as I don't have Forscan.

I find it hard to imagine that it really makes any difference, given the probably millions of Fords running around all over the world whose owners have never given a thought to this when changing a battery. Most have probably not even read the Manual! However, given the technology is fitted to the vehicle I would like to try to utilise it.

 

[FrogXA]

When I bought my last battery, I asked the bloke at the battery place about the positive battery corrosion problem and he said " it's just a Mustang problem" and mentioned nothing about the battery reset so I think a lot of people have this corrosion and other problems because they don't know about the reset. I went home and did some research on the net and came across the above procedure.

As you say, the technology is there for a reason so you might as well use it considering how easy it is to do. It's a shame this knowledge isn't more readily available to the average owner.

 

[Ozcraig]

Yes, I'm sure the kid who fits you a new battery at Supercheap has no idea, and probably the professional mechanic with RACQ doesn't know the process either. The Manual supplied with my 2017 car, which is probably the same as yours, doesn't even mention it, yet the Dealer Service Manual calls for the whole Forscan reset. Confusing for the average owner.

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