Help me Find the Cause

[WItoTX]

Looking for some help. I have a 2017 GT350, and am running into some electrical issues. I have a parasitic draw on my battery of about 1.2 amps. So far, I have only tested under the hood fuses, but found two fuses that seem to be the culprit.

Fuse 24 – Voltage Quality Module - ~.7 amps

Fuse 28 – Automatic Brake System Valve - ~.25 amps

As best I can tell, the VQM makes sure the power going to everything is smooth. So I guess I am not shocked it has some voltage at all times, especially since my key is probably closer to my car than it should be. The Automatic Brake System Valve is the one that I think might be the culprit. In addition to drawing .25 amps, when I run my forscan, I get a code for the ABS, code U0122 – Lost Communication with Vehicle Dynamics Control Module. It might potentially be related.

I have a couple courses of action to take to start diagnosing. First, do I have a bad ground? Does anyone know where the ground is for the brake system? Or know where I can find a wiring diagram? I’ve already cleaned the ground near the battery, one that is a common culprit, along with the ground under the intake box.

Secondly, I always have a OBDII hooked up. So I am going to pull that off tonight.

Third, I threw the car on a maintainer last night (brand new battery), and pulled it off this morning. This morning it was showing 12.7 volts, and so I am curious what it will show this evening when I get home.

Finally, I didn’t do the passenger fuse panel, but its 100 plus degrees here, and I was lazy last night. It’s on my list.

My gut (Which is usually wrong) tells me fuse 24 (VQM) is engaged any time something is drawing power on the car. So it probably is a symptom, not the root cause. I suspect 28 is my issue. If anyone has any idea, or similar history with fuse 28, I am all ears. Thanks!

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[NGOT8R]

I had an issue with my 2019 Bullitt‘s battery constantly draining and requiring a jumpstart about 2 years into ownership. I read information online somewhere, that failure to lock the doors and keep the key fob away from this was causing a significant draw on the battery because the car was always searching for and trying to detect the fob. I replaced my battery a year ago and have been locking my doors ever since and so far, I haven’t had any further issues.

 

[WItoTX]

I had an issue with my 2019 Bullitt‘s battery constantly draining and requiring a jumpstart about 2 years into ownership. I read information online somewhere, that failure to lock the doors and keep the key fob away from this was causing a significant draw on the battery because the car was always searching for and trying to detect the fob. I replaced my battery a year ago and have been locking my doors ever since and so far, I haven’t had any further issues.

I've read that as well (seen your avatar IIRC on a couple threads), and it's definitely on my list of things to change going forward.

Thanks!

 

[WItoTX]

Anyone?

 

[MiamiGT350]

I get a code for the ABS, code U0122 – Lost Communication with Vehicle Dynamics Control Module.

Trying to locate the source, but I believe this is related to the car being on a battery tender when the vehicle is started. I have also seen an "ABS voltage higher than expected" error from time to time.

Just wanted to mention it before you go too far down a rabbit hole. You may want to clear codes and ensure you start the car without the battery tender.

 

[WItoTX]

Trying to locate the source, but I believe this is related to the car being on a battery tender when the vehicle is started. I have also seen an "ABS voltage higher than expected" error from time to time.

Just wanted to mention it before you go too far down a rabbit hole. You may want to clear codes and ensure you start the car without the battery tender.

Man, that would be wild if that was the case. I kept the codes just so I could track them, but I'll clear them out tonight and see if it comes back.

 

[Inthehighdesert]

I leave the fobs in the center console on both my cars. My 350 is on a tender and theres no issue’s as would be expected. My 500 is not, and that car can go weeks at times between being started. Neither have issue’s with battery’s. Now my 16 Gt is a different story. That car is finicky when sitting. That car seems to cycle itself a lot more often then my other two. My wife refers to it as R2D2 is going off in the garage again. I wonder if there’s something a little different in the programming on the cars between years.

 

[WItoTX]

Update: I am eliminating the easy causes first to see if that resolves my problem (I usually pick the hardest, most expensive ones first for some reason). Yesterday morning, I pulled the car off the maintainer. Immediately after that, the battery was at 12.7 volts. I locked the car, left the trunk open (to get to the battery) and threw the key inside the house (Probably 25' or so away from the car). That was 4.15 am.

Got home around 4 pm, and tested the battery. Still at 12.7 volts. I decided to leave everything as is, and test it in the morning. Well, I tested it this morning, and it's still sitting at 12.7 volts.

The battery dropped 1 volt in one day, with the key in the car, and the car unlocked. The battery stayed at 12.7 volts in one day, with the key hidden away, and the doors locked.

It's looking promising that that locking the car and removing the key is the trick. Regardless of the reading tonight, I am going to clear out those codes, and see what comes back. There are two grounds above the interior fuse panel that the previous owner ran a power cable for his subs past. I need to pull out the passenger seat and see if either of those are jacked up too.

 

[WItoTX]

I leave the fobs in the center console on both my cars. My 350 is on a tender and theres no issue’s as would be expected. My 500 is not, and that car can go weeks at times between being started. Neither have issue’s with battery’s. Now my 16 Gt is a different story. That car is finicky when sitting. That car seems to cycle itself a lot more often then my other two. My wife refers to it as R2D2 is going off in the garage again. I wonder if there’s something a little different in the programming on the cars between years.

The thing I would point out with that, if there is a draw, you are basically working the battery harder, and cycling it more, by doing it that way. I am wondering if that is why my LiPo battery can't handle the power requirements in this car, because that is exactly what I did. The car was on a maintainer, except for track days, and it took just a couple months before I was having electrical issues.

 

[WItoTX]

Update. This morning, tested the battery with the car locked, and key in the house. The battery is holding solid at 12.7 volts. I would imagine a significant drop if the car truly had a parasitic drain by now.

4 pm today will be a full 48 hours since it was on the maintainer. If there is no drop, I think I have resolved my issue.

What is really annoying is, now my wife is going to say, "see, I told you so". She has always locked her car and brought keys inside just because that is how she was raised, and it drove me nuts. Maybe I just won't tell her.

 

[72&18]

Update. This morning, tested the battery with the car locked, and key in the house. The battery is holding solid at 12.7 volts. I would imagine a significant drop if the car truly had a parasitic drain by now.

4 pm today will be a full 48 hours since it was on the maintainer. If there is no drop, I think I have resolved my issue.

What is really annoying is, now my wife is going to say, "see, I told you so". She has always locked her car and brought keys inside just because that is how she was raised, and it drove me nuts. Maybe I just won't tell her.

Dude, you can't tell her. Just let it die. I would guess she won't bring it up. However, in about two weeks she will notice the keys being inside and burn you on it.....

 

[WItoTX]

Dude, you can't tell her. Just let it die. I would guess she won't bring it up. However, in about two weeks she will notice the keys being inside and burn you on it.....

Oh I am well aware of what is coming. And it's not the first time something similar has happened, and I am 100% certain it will not be the last.

I am more worried about when my kids start being right.

 

[MAGS1]

Oh I am well aware of what is coming. And it's not the first time something similar has happened, and I am 100% certain it will not be the last.

I am more worried about when my kids start being right.

When my kids start being right, I’m checking myself into the old folks home

 

[Nfs1000f]

I have a 2017 as well. I’ll leave the key fob in the car at least once a week for a couple of days. I’m still on the OEM battery that is now seven years old. Have had no issues.

 

[WItoTX]

I have a 2017 as well. I’ll leave the key fob in the car at least once a week for a couple of days. I’m still on the OEM battery that is now seven years old. Have had no issues.

I decided to leave my car unlocked, and key in it to see how fast the drain is. This morning it's down a bit, like .05. definitely less than I expected. Going to track for a few days just for information.

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