Battery Management System Reset

[Zinc03svt]

Just curious and looking at the location of the sensor plugs in my 2018 automatic's engine compartment, I was dismayed that the positive connector wasn't visible like Smokey's. I found it under a monstrous piece of equipment. What the heck is that? Seems as if someone drew a line on it with a silver Sharpie™. Negative cable sensor looks normal.

Not that I'd ever consider disconnecting something Ford clearly invested a great deal of engineering in, just to get my possibly innocuous gauge readings in a line.

That monstrous piece of equipment is called a fuse box. I have found my car seems to idle and drive better without my voltage continuously going up and down with the battery mgt plugged in. It now holds consistent 14.1 to 14.6 volts. The lowest I have seen unplugged was 13.9 and it quickly popped back up to 14.1. Prior plugged in it would drop down to 12.1 to 12.5 which is dead battery range. Fyi

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[GT Pony]

Prior plugged in it would drop down to 12.1 to 12.5 which is dead battery range. Fyi

FYI ... the voltage displayed on the dash typically reads 0.4~0.5 volts less than the voltage right across the battery terminals.

 

[frank s]

That monstrous piece of equipment is called a fuse box...

I'm pretty sure I have identified the Fuse Box. What is confusing to me is the Monster, which doesn't appear in Smokey's photos. If it's not something added to the Monitoring System, what is it? An external fuse? Seems pretty elaborate to be that.

 

[H1shawn1]

So I went ahead and replugged my sensors in after disabling BMS in forscan and voltage remained unchanged in the mid 13s. I then went ahead and re-enabled BMS to do a battery reset in forscan, after doing so I immediately disabled BMS and am now seeing better voltage. Fluctuates between mid 14s and high 13s.

I'm now finally happy with my charging system and will reply to post if I notice any side affects from the changes.

 

[CompOrangeFanatic]

I just replaced my factory battery yesterday as it took a dump(about 4.5 years old), only showed it had 5V's when tested after only sitting a day without the car being driven. I did have some battery corrosion on the negative terminal prior which I cleaned up before the battery totally died. I read through this thread and have been watching my voltage in the display. Even with the new battery, I see voltage go down to 12.1 at times, then 12.4, 12.9, 13.3, 13.7, etc. BMS must be doing its thing. Debating on whether to disconnect it or not.

 

[H1shawn1]

I just replaced my factory battery yesterday as it took a dump(about 4.5 years old), only showed it had 5V's when tested after only sitting a day without the car being driven. I did have some battery corrosion on the negative terminal prior which I cleaned up before the battery totally died. I read through this thread and have been watching my voltage in the display. Even with the new battery, I see voltage go down to 12.1 at times, then 12.4, 12.9, 13.3, 13.7, etc. BMS must be doing its thing. Debating on whether to disconnect it or not.

What you are seeing is most definitely the BMS doing it's thing, in your situation I probably wouldn't bother changing anything. If you have forscan it wouldn't be a bad idea to do a BMS reset, or you could ask for one that next time you are at your dealer.

 

[CompOrangeFanatic]

What you are seeing is most definitely the BMS doing it's thing, in your situation I probably wouldn't bother changing anything. If you have forscan it wouldn't be a bad idea to do a BMS reset, or you could ask for one that next time you are at your dealer.

Yea, I'll probably leave the BMS connected for now unless I start having weird problems. I don't have a forscan. Car seems to be working fine and starting up quicker since I installed the new battery.

 

[Adz]

My battery drained to 2v last night and waking up the neighbours with the alarm going crazy.

I have a 2019 UK/EU spec GT I have disconnected the negative sensor, but oddly enough the positive sensor doesn't even have a connection?! The sensor is there but there is no connector coming off the harness so isn't even connected!

 

[GT Pony]

If you place the battery on a modern charger system and obtain a fully charged battery of 12.75 volts, the BMS wont detect that and revert to normal mode?

Sounds like what he said in the video that was posted in Post #6 is that it will reset by itself if the car is left alone for 8 hrs



So sounds like if you fully charged the battery and left the car sit undisturbed for 8 hrs the BMS should reset itself without using a scan tool. Per the video, the scan tool is to bypass that long 8 hr sitting period.

Also, note what is said in this info from the service manual concerning battery charging. They also mention in the third paragraph that the 8 hr undisturbed sitting period is required if the scan tool is not used to reset the BMS.

 

[Diocletian]

Been chasing problems involving my Lund tune for over a year. After analyzing log after log I noticed my idle surging/stalling issues lined up exactly with voltage dips as low as 12.2v. I decided to try to disconnect the BMS as multiple tune revisions did nothing.

So I disconnected the 2 plugs shown, exactly like how another users picture shows. Now my hood will not latch closed.

I did not do anything to the hood latch at all, nothing is in the way or has been moved to cause this. I have tested to make sure my car still has full power and it does, but with these plugs disconnected I cannot get the hood to close, what's going on?

 

[H1shawn1]

Been chasing problems involving my Lund tune for over a year. After analyzing log after log I noticed my idle surging/stalling issues lined up exactly with voltage dips as low as 12.2v. I decided to try to disconnect the BMS as multiple tune revisions did nothing.

So I disconnected the 2 plugs shown, exactly like how another users picture shows. Now my hood will not latch closed.

I did not do anything to the hood latch at all, nothing is in the way or has been moved to cause this. I have tested to make sure my car still has full power and it does, but with these plugs disconnected I cannot get the hood to close, what's going on?

They are unrelated, nothing about the hood latching is electrical. Most likely there is something you are missing that's impeding the hood. Take a break, and come back with a fresh eyes. Go over everything one more time, eventuality the issue will reveal itself.

 

[Zinc03svt]

Yeah I run with mine unplugged no issues. It stalled first time in 5 months with them plugged in. Some people think I’m over charging my battery, but car runs better at idle with them disconnected.

Has dealer checked your cam phasers?

Yeah, hood latch should not be related in any way. Good luck with that. ;).

 

[Diocletian]

It was a god damn prop rod, I got to get rid of that thing. Even my base 2006 4Runner has hood struts lol.

Hopefully this fixes my surging issues. I'll be testing it later today

 

[H1shawn1]

It was a god damn prop rod, I got to get rid of that thing. Even my base 2006 4Runner has hood struts lol.

Hopefully this fixes my surging issues. I'll be testing it later today

Dude those types of things are the worst. There isn't a man alive who wrenches on their car that hasn't nearly had a heart attack because they overlooked the most basic thing.

 

[Bahndvr]

Been chasing problems involving my Lund tune for over a year. After analyzing log after log I noticed my idle surging/stalling issues lined up exactly with voltage dips as low as 12.2v. I decided to try to disconnect the BMS as multiple tune revisions did nothing.

So I disconnected the 2 plugs shown, exactly like how another users picture shows. Now my hood will not latch closed.

I did not do anything to the hood latch at all, nothing is in the way or has been moved to cause this. I have tested to make sure my car still has full power and it does, but with these plugs disconnected I cannot get the hood to close, what's going on?

I had 'on brake idle hunt' and Lund tuned it out.

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