Battery Management System Reset

[frank s]

It is just the BMS system not resetting after the car sits. I’m sure a hard reset will force it to reset but why wouldn’t it just reset on its own like it’s supposed to. All you lose by disconnecting is the “smart charging” but it’s not really smart if my battery didn’t even last 3 years lol

I don't know what is responsibe for the change, but where the shutoff occurred at thirty minutes and ten minutes after a re-try, this evening it allowed forty minutes twice in a row. Then I did the FORScan reset routine, but didn't wait around for more than fifty minutes to see if it was going to quit. Volts were 12.4 at the beginning, 12.1 when I abandoned it. Previous closings wre at 11.8 or less.

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[frank s]

I dont buy any communication between BMS and the charger ask the charger tech support.

You're probably right.

"In this universe there are things
that just don't yield to thinking
—plain or fancy— Dude".
—J. Spicoli, PolyPartyPerson

 

[chowman90]

Where do you find to reset using the Forscan program?

 

[frank s]

Where do you find to reset using the Forscan program?

Module is called "BdyCM", oddly enough.

 

[Smokey613]

I know this is an old thread but what are the steps to disconnect the BMS? I have been unable to locate any for the Mustang. There are several out there for the F150.

 

[melwff]

You have an advanced battery charger telling you the battery is bad and voltage readings of 12.4 and 11.8 or less which is a dead battery. You probably have a defective battery. Take it back to where you bought it and have them load test it.

 

[thehunterooo]

I know this is an old thread but what are the steps to disconnect the BMS? I have been unable to locate any for the Mustang. There are several out there for the F150.

There are two current relays that you disconnect if you want to disable the dumb charging. The BMS system itself is okay if it isn't allowed to control the charge on the battery. I do not have my car anymore but I will try to find the pictures of the two if I can. It is pretty easy.

 

[Smokey613]

I am not having any issues currently but it would be nice to have the information if needed. It seems things like this always happen after 5 or on the weekend.

 

[ChristianDev]

I'm having the same low battery mode problem where it cuts off accessories to preserve the battery. It cut off my power steering too. I've only had this problem when the car sits for a few days and even when I recharge the battery it wont come out of low power mode. Is there a way to reset the BMS or is it only through Forscan

 

[DetroitMustang]

There are two current relays that you disconnect if you want to disable the dumb charging. The BMS system itself is okay if it isn't allowed to control the charge on the battery. I do not have my car anymore but I will try to find the pictures of the two if I can. It is pretty easy.

I used forscan to reset the BCM. It seemed to work all day, but after sitting overnight it went back to jumping all over the place. So I checked for DTCs and it came up with this:

===BdyCM DTC B1438:03-08===
Code: B1438 - Battery Current Sensor

Additional Fault Symptom:
- Frequency Modulated / Pulse Width Modulated Failures

Status:
- Previously Set DTC - Not Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC.

So now I have to try and convince the dealer to do something about it..
They already said before it's "normal".

On a side note, I reset the trans adaptive learning and now it drives so smooth, no more harsh shifts and lurching.!!

 

[thehunterooo]

I used forscan to reset the BCM. It seemed to work all day, but after sitting overnight it went back to jumping all over the place. So I checked for DTCs and it came up with this:

===BdyCM DTC B1438:03-08===
Code: B1438 - Battery Current Sensor

Additional Fault Symptom:
- Frequency Modulated / Pulse Width Modulated Failures

Status:
- Previously Set DTC - Not Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC.

So now I have to try and convince the dealer to do something about it..
They already said before it's "normal".

On a side note, I reset the trans adaptive learning and now it drives so smooth, no more harsh shifts and lurching.!!

Sounds like one or both of the sensors are bad. I would personally just disconnect them both and never worry about the silly charging system again. Otherwise the sensor shouldn’t be too crazy to replace if not under warranty.

 

[Smokey613]

I have been wearing Google out trying to locate these sensors but to no avail. If it was an F-150 it would be a piece of cake as there is plenty of info on them.

 

[Zinc03svt]

Sounds like one or both of the sensors are bad. I would personally just disconnect them both and never worry about the silly charging system again. Otherwise the sensor shouldn’t be too crazy to replace if not under warranty.

Where are the sensors located??

 

[DetroitMustang]

I took it to the dealer and spoke to the service manager. He seemed to know what I was talking about. I showed him the DTC .
So I left it there and hopefully they fix it. It is under warranty.

BTW the sensor is on the negative cable, just towards the windshield. You'll see a plug . It's only about a $15 part. Simple to replace.
I don't know where the other one is.

 

[thehunterooo]

There is one right of the neg terminal as mentioned. The other one of near the fuse box to the right of it. I wish I still had my car I would get pics

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