Is battery management module necessary?

[rallytaff]

We're supposed to reset the charging system following a battery swap or charge.
https://www.fiestastforum.com/threads/battery-monitoring-system.25904/post-478335

https://www.fiestastforum.com/threads/agm-battery-concerns.24120/

Didn't have to do it when I changed batteries. Everything still worked as it should. I wouldn't know how to anyway!

 

[Intuit]

Hmm. Not helpful. I guess the clerk just wanted you to come in. (what I always do with my local one)
https://www.bing.com/images/search?q=DU2Z-14S411-AZB
Image search seems to just point to a connector.

One of these what you're seeking?
https://www.fordpartsgiant.com/part...rical/battery_cables_and_horn.html?pnc=10C679

 

[Capri to ST]

We're supposed to reset the charging system following a battery swap or charge.
https://www.fiestastforum.com/threads/battery-monitoring-system.25904/post-478335

https://www.fiestastforum.com/threads/agm-battery-concerns.24120/

Thanks for posting this, and I'm glad to know it, but it occurs to me that it is probably almost never done. I would bet that almost all batteries are changed without anyone resetting their battery monitoring system.

I'm curious, has anyone on here ever reset their battery monitoring system after a battery change?
If so, did you use the procedure mentioned in the link (which is for a MK8 FiST), or how did you do it?

 

[Intuit]

I'm curious, has anyone on here ever reset their battery monitoring system after a battery change?

Quick & friendly poll...
https://www.fiestastforum.com/threads/poll-battery-monitor-system-bms-reset.31882/

Me? No... but I will going forward... and probably tomorrow. Whether it's my cars or motorcycles, my batteries seem to have relatively short lives.

 

[SteveS]

After some research I found that ALL Fords with a battery management module are reset this way after a battery change. Apparently without the reset the module thinks it is still dealing with a weak battery and may throw battery-related codes or not operate some computers correctly. It may also not charge the new battery correctly.

 

[Capri to ST]

After some research I found that ALL Fords with a battery management module are reset this way after a battery change. Apparently without the reset the module thinks it is still dealing with a weak battery and may throw battery-related codes or not operate some computers correctly. It may also not charge the new battery correctly.

When you say they are reset this way, what method of resetting are you referring to?
I'm just trying to confirm whether the reset procedure referred to in the video link above is the correct one, or whether there's some other reset procedure, thanks.

 

[Intuit]

In the linked thread, @Sprinkle_Star confirmed it worked.

Given how wildly different a battery can perform at 2 degrees versus 92 Fahrenheit, I'm curious whether BMS takes temperature into account?

 

[rallytaff]

After some research I found that ALL Fords with a battery management module are reset this way after a battery change. Apparently without the reset the module thinks it is still dealing with a weak battery and may throw battery-related codes or not operate some computers correctly. It may also not charge the new battery correctly.

My car starts first time in the mornings whether it's warm or cold outside. Never had any codes show. Everything on the car works as it should. Maybe I'm one of the lucky ones?

 

[fun with fisting]

Hmm. Not helpful. I guess the clerk just wanted you to come in. (what I always do with my local one)
https://www.bing.com/images/search?q=DU2Z-14S411-AZB
Image search seems to just point to a connector.

One of these what you're seeking?
https://www.fordpartsgiant.com/part...rical/battery_cables_and_horn.html?pnc=10C679

So that part you linked, negative terminal and sensor assembly (CV2Z-10C679-C ) I have already ordered.

I am in need of the connector and pigtail to plug in the sensor. I’ll have to cut the old connector off my wiring loom and splice in the new one.

 

[Intuit]

Wow. They want $100 for that cable and box...

 

[SteveS]

When you say they are reset this way, what method of resetting are you referring to?
I'm just trying to confirm whether the reset procedure referred to in the video link above is the correct one, or whether there's some other reset procedure, thanks.

I was referring to the method. Turn car on without starting engine. After dash has completed its initial light blinking, pull turn signal to flash the brights 5 times, then press the brake pedal 3 times. Wait. After a few seconds the battery indicator light on the dash will blink and then go steady. Then start engine.

My car starts first time in the mornings whether it's warm or cold outside. Never had any codes show. Everything on the car works as it should. Maybe I'm one of the lucky ones?

I had replaced the battery on the Fist about a month ago, and last week had to replace the battery on my F150. I did not do the reset procedure, and they both worked perfectly fine after swapping the battery without codes. I performed the procedure of flashing the brights and pressing the brake pedal on both car and truck after I read about it to see what it did. The battery light did blink as it was supposed to. But There is no discernible difference before or after in how they start and drive. And I had gotten no check engine lights in either one. I would guess that getting codes or apparently even the vehicle not starting after a battery swap is the exception, not the rule.

However what I have read from different Ford technician Q&A sites is that not resetting the BMS can reduce new battery life by a year or more by not charging the new battery properly, lead to drivability problems because of not delivering full voltage to all the computers and shutting off the computers every time the car is shut off, leading to having to relearn or not saving learning. Those last couple of things can lead to check engine lights or even failure to start if severe enough. It all seems to hing on how bad the old battery was and how long you drove it while it was delivering low voltage and not receiving charge properly.

 

[Capri to ST]

I was referring to the method. Turn car on without starting engine. After dash has completed its initial light blinking, pull turn signal to flash the brights 5 times, then press the brake pedal 3 times. Wait. After a few seconds the battery indicator light on the dash will blink and then go steady. Then start engine.



I had replaced the battery on the Fist about a month ago, and last week had to replace the battery on my F150. I did not do the reset procedure, and they both worked perfectly fine after swapping the battery without codes. I performed the procedure of flashing the brights and pressing the brake pedal on both car and truck after I read about it to see what it did. The battery light did blink as it was supposed to. But There is no discernible difference before or after in how they start and drive. And I had gotten no check engine lights in either one. I would guess that getting codes or apparently even the vehicle not starting after a battery swap is the exception, not the rule.

However what I have read from different Ford technician Q&A sites is that not resetting the BMS can reduce new battery life by a year or more by not charging the new battery properly, lead to drivability problems because of not delivering full voltage to all the computers and shutting off the computers every time the car is shut off, leading to having to relearn or not saving learning. Those last couple of things can lead to check engine lights or even failure to start if severe enough. It all seems to hing on how bad the old battery was and how long you drove it while it was delivering low voltage and not receiving charge properly.

Thanks for the information, that's helpful. When I first hear about a new procedure like this I want to make sure it's really needed, that I'm not inadvertently hurting something while trying to help.
I did some reading on it myself after reading your post, and did find some indication that the system may relearn on its own after a certain period of time. However, there's no certainty that this happens, so it seems like this manual reset procedure is something worth doing, that there's no reason not to, and it may help.
I had a new Advance Auto AGM battery put in 3 and 1/2 years ago by an independent shop that I trust. I don't know whether they did the battery monitoring system reset, but would be surprised if they did . Everything's working fine, but I'm going to get another one next summer and will probably do the reset procedure then just to be on the safe side.

 

[fun with fisting]

Wow. They want $100 for that cable and box...

yeah ridiculous huh. My local dealer wanted $140 for that part.

I will be trying out an AGM battery when I get these parts in. I just replaced my battery with a brand new motorcraft BXT96R500 (thinking it would alleviate my corrosion problem) and it’s already causing more rapid corrosion buildup than my original battery.

There are even droplets of liquid on top of the battery casing right at the terminals which I assume is probably battery acid. I’ll definitely be trying to return this battery to the dealer.

 

[SteveS]

Here's a video about what the BCM does which illustrates why it is a good idea to reset after replacing the battery.

View: https://youtu.be/I_KmO-KaR4A?si=dnrwnxjRUisRXNxH

 

[M-Sport fan]

Since I must disconnect the negative terminal in order to get the CD player to eject the disc every other time I use it, I will do this procedure the next time I disconnect/reconnect the battery.

THANKS for posting the procedure steps!

 

[contemplative_shrimp]

Wow. They want $100 for that cable and box...

I ended up getting one off ebay, probably taken off a junkyard scrap. Pretty ridiculous how difficult/expensive Ford made getting this easily damaged part.

 

[Intuit]

Personally I'd pay the $100 before trusting FleaBay LoL. (got sick of the nonsense from sellers)

 

[contemplative_shrimp]

Personally I'd pay the $100 before trusting FleaBay LoL. (got sick of the nonsense from sellers)

A few months ago when I was dealing with a corroded negative cable, every Ford shop was out of stock and backordered... couldn't even drive the car with no place to purchase a new cable. Ebay was the only option unfortunately.

 

[Intuit]

Yeah sometimes you run into that situation. In the past (different car) I've called around to various different junkyards within 30 miles to get a part.

 

[Capri to ST]

For those doing the battery monitoring system reset, once you've done it the battery / charging system warning light on the dash is supposed to blink and then go out. Here's a picture of it so people will know where it is and what it looks like. These warning lights come on briefly on startup and then turn off after about a second.