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You could be dealing with the early stages of a failing alternator.
Thanks for the suggestion. Is there any metric in the AP3 (Battery V?) that would be an indication of alternator health? My AP3 shows 14.50 V while idling (immediately after startup) and 13.50 V (Battery V) while driving after the car is warm.

I'm also wondering if there is any way to verify that the BMS reset was effective. All I saw as a confirmation was the battery indicator light blinked two times- but I'm wondering now if the BMS reset was done correctly and has been reset. Is there a way to verify? Could replacing the battery and not resetting the monitor (even though I believe I did) cause the battery light to come on intermittently?
 

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@Mzdrati I believe voltage is an option on the ap3. Although I've never looked for it but I think I remember seeing it in passing.

And if the battery light blinked you're good.

You can get in there with forscan, I've seen someone here mention there's a PID indicating "battery age" In days. Which would obviously reset to zero when you do the BMS reset.
 

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@Mzdrati I believe voltage is an option on the ap3. Although I've never looked for it but I think I remember seeing it in passing.

And if the battery light blinked you're good.

You can get in there with forscan, I've seen someone here mention there's a PID indicating "battery age" In days. Which would obviously reset to zero when you do the BMS reset.
Yup, there's a battery age PID. That's how you figure out you're on borrowed time with your 2365 day old and counting Motorcraft original.... (just moved jump pack from wife's car to mine). Hopefully SSgtjrobertson doesn't see this -- but it's getting replaced on the 15th, I promise.

You can also go to tools and do a BMS reset if it didn't take before, once you're in FORscan. I had never used it before until last week, and it seems pretty straightforward. I don't play around with any of the AS_BUILT stuff that allows you to nuke your car though.
 

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Yup, there's a battery age PID. That's how you figure out you're on borrowed time with your 2365 day old and counting Motorcraft original.... (just moved jump pack from wife's car to mine). Hopefully SSgtjrobertson doesn't see this -- but it's getting replaced on the 15th, I promise.

You can also go to tools and do a BMS reset if it didn't take before, once you're in FORscan. I had never used it before until last week, and it seems pretty straightforward. I don't play around with any of the AS_BUILT stuff that allows you to nuke your car though.
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I was on the road today for work, and drove 250 miles and the Battery Light didn't come on at all. In fact- it hasn't come on since last Thursday when I posted about it. I don't get it. I had a CEL last year and the car ran rough- for no reason at all. It was unrepeatable, resolved after a restart, and hasn't happened again ever.

I hope the Battery Light issue was just a fluke too... I know all complex electronics are subject to stray technical errors from time to time- and a restart sometimes resolves minor glitches.

I'm curious about something, though: since the Battery Light popped up 4 days ago I have been monitoring my "Battery V" on my AP3. I know this is the precise reason people do NOT want to use these "Anxiety Port" devices, because now I'm looking at what the voltage the battery shows, (monitoring to see if it shows anything "out of the ordinary" which I'd notice as less than 13V or more than 15V) and sometimes it's 14.50V while driving, and sometimes it's 13.50 V. I'm guessing that the computer decides how much power to deliver to the battery from the alternator, and it may change depending upon a number of factors- so I guess I'm wondering if in general there is anything specific I should look for with respect to that "Battery V" value that might indicate a problem with the alternator or another component or connection.
 

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I leave mine in glovebox.
 
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I guess I'm wondering if in general there is anything specific I should look for with respect to that "Battery V" value that might indicate a problem with the alternator or another component or connection.
Yes, the battery light. Your voltage will vary wildly depending ECM requirements. When desired output doesn't meet the command, that's when it turns the battery light on.
 

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I leave mine in glovebox.
I owned my AP3 for about a year before I installed it, because I didn't want to stare at a bunch of numbers that I know I do not understand, and which I assumed can only cause anxiety and stress. Turns out- I really like having some of the data up and displayed. The precise boost pressure, for example... If I'm cruising in 5th or 6th gear, and want to increase my speed slightly- I can glance over and be sure to keep the Boost Pressure in a negative range, so as not to get into boost in a high gear instead of downshifting. The stock boost gauge does not provide enough detail to allow you to do that. I also like to see my oil pressure and oil temperature. I know I am supposed to monitor "Ign Cor" (Ignition Correction) for cylinders 1 and 4, but I do not launch or beat on my car often, and those figures do not seem all that helpful to me day to day. Same with LTFT and OAR... Monster Tuned advises to keep an eye on both, but LTFT always stay well below the 12% that is the stated max, and my OAR had remained at -1.00 ever since I got it there the first few days after flashing the tune. As much as I thought my AP3 would end up in my glovebox- it has remained on the magnetic mount and I have been enjoying it quite a bit more than I anticipated.
 

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Check the BMS sensor for corrosion. (Connector & sensor body) Also check that the white wire leading from the red battery terminal doesn't have any corrosion as thus powers the BMS sensor.

With the vehicle at Idle measure voltage at the battery. Should be around 14 VDC.

Yes if the AGS (or alternator) connectors have moisture trapped this can also cause a battery light to trigger.

The components you added did not cause this to happen.

I believe that a 96R is the correct size battery. If you switch size or styles the PCM must be updated to reflect this change
The "Battery Light" came back on again for awhile yesterday for awhile. When it does- there is no detectable change in the way the car operates, and it runs and drives as it should. Another interesting occurrence also happened: at cold startup (after the car sat for ~3hours while I was at my night job) I turned the car on, and it started up normally- but the center screen (ST3) was solid blue for a second- then a warning popped up stating that the rear camera is either not available or not connected. This confirms to me that there is definitely something going on with this car. I recently hardwired a dashcam and drove the car for a week without any issues or problems, then installed a new battery, and the car worked perfectly fine for another few weeks before I saw a battery light warning, and now this odd center screen behavior. I read through the "Key Not Detected" thread, and it was very interesting, but did not yield a resolution in my specific case.

I know you stated that my hardwiring has nothing to do with any of this- but I am considering unplugging the add-a-fuse connected to F85 (and inserting the fuse as when stock) to see if that has any effect. Fuse 85 is stated as follows in the Owners Manual:

Font Rectangle Magenta Paper product Number


I'm wondering what "voltage quality monitoring" is, and if I have a constant draw on that circuit- (used for my dash cam "Parking Mode") if it's causing these problems.

For the record- I wanted/intended on utilizing F61 as you suggested in your masterful writeup about adding fuse taps, but F61 is right up against a large connector, which prevents an Add-a-Fuse from fitting. Is there a different type of mini Add-a-Fuse that would work in F61?
 

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If you installed the fuse tap correctly (which I know you did) the it will not effect the BCM. You are tapping into one of two 50 amp (100 amps total) supply voltage.

The system is triggering the battery light because either 1. The battery is failing to supply the system with enough voltage or 2. The alternator is failing to supply the system voltage to maintain the battery.

Your battery is new and not a refurbished unit. Remember that the alternator output runs directly to the starter and then onto the HVJB (high voltage junction box) mega fuse #2. From there it connects to everything.

So reading voltage at the battery is fine to check the Alternators output but may not represent the actual voltage available at the system level. Corrosion, poor grounds, moisture, burnt relay contacts or a combination of them can effect the system as a whole. Adding such a small amount of load to BCM will not effect that system.

I believe it's time to start looking at the cables that feed the system.
 

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I understand. That will be my next step... taking the airbox out and inspecting the grounds in that location. DMC took the negative battery terminal off of the firewall of my car when my car was at his "shop" over a year ago- and he ground paint off and re-secured that cable- so I doubt that is the problem.

I was thinking that the "voltage quality monitoring" (whatever that is) might detect the parasitic loss of the Garmin Parking Mode Cable that is on that F85 circuit which keeps the dash can powered up during a prescribed amount of time while the car is parked (off), potentially making the car unhappy.

I'll work on inspecting the ground wires, and will report back. Thank you again for your assistance!
 

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I understand. That will be my next step... taking the airbox out and inspecting the grounds in that location. DMC took the negative battery terminal off of the firewall of my car when my car was at his "shop" over a year ago- and he ground paint off and re-secured that cable- so I doubt that is the problem.

I was thinking that the "voltage quality monitoring" (whatever that is) might detect the parasitic loss of the Garmin Parking Mode Cable that is on that F85 circuit which keeps the dash can powered up during a prescribed amount of time while the car is parked (off), potentially making the car unhappy.

I'll work on inspecting the ground wires, and will report back. Thank you again for your assistance!
Before you start ripping your work out just try removing the fuses to the items you've added and see if the problem remains. No point in spending money of stuff you don't need.
 
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Before you start ripping your work out just try removing the fuses to the items you've added and see if the problem remains. No point in spending money of stuff you don't need.
Understood and agree; I was just thinking ahead. If by chance the issue was caused by using F85 (when F61 would be a better choice) I was wondering if there is a slimmer mini fuse tap that will work in F61, since the standard mini fuse taps that I have tried will not seat properly. The fuse box housing interferes with the Add-a-Fuse and it cannot be pushed in far enough to work in that location. I see online that there are "Low Profile" versions, but I do not see a difference between them and the standard mini fuse taps that I have.
 
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