Charging System Service Now - Argh

[Angrey]

Hi guys I'm having sort of the same issue. Two dealers and two auto electrical shops in. I'm still having the same issue. I'm on my third alternator and same issue.
My problem is that the voltage some time goes too high causing the dash lights to dim. I've seen as high as 16.1V and nobody seems to be able to fix the car.$$$$$$ = 0 results

There's something in the system that's causing it to think the battery is WAY depleted. Have you checked and/or replaced the grounds, battery, etc.

The BMS spikes the voltage when it goes into a recharge state and attempt to recover the battery back to charge. So something in the system is telling it that the battery is dead or near dead and to go crazy high on the voltage.

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[MiamiGT350]

Last time I performed a BMS reset for a friend, I was playing around in Forscan settings. I noticed that you can define the type of battery for the BMS to manage. From memory, the drop-down was a bunch of CCA choices and battery types. Is it possible that the BMS would manage the ATX-20 type batteries if this setting was modified to something that matches the battery profile?

Note: I don't recall if any Lithium batteries were listed, so my point may be moot.

 

[galaxy]

Knock on wood, but ~8K miles on my 20HD with zero issues, and I know a handful of other buddies in the same boat. My electrical system is bone stock with no aftermarket demands, so can’t speak to if that makes a difference, but mines been stock perfect. Voltage doesn’t look different from a stock battery or anything. Nada.

 

[Evolvd]

Last time I performed a BMS reset for a friend, I was playing around in Forscan settings. I noticed that you can define the type of battery for the BMS to manage. From memory, the drop-down was a bunch of CCA choices and battery types. Is it possible that the BMS would manage the ATX-20 type batteries if this setting was modified to something that matches the battery profile?

Note: I don't recall if any Lithium batteries were listed, so my point may be moot.

No, just standard LA and AGM

 

[RobeRob]

Yeah I took it to the dealership. They had a Shelby guy there. He said the A,B wire pins at the alternator were pushed out so he pushed them back in. The car drove for a few days only to do the same thing again.
I'm thinking it may be the alternator plug

 

[ChipG]

Ok, an update on this issue (and not a positive one):

At this point I have replaced the engine wiring harness, the battery harness, and the alternator (with a new OEM unit) since last post. The only change in behavior is that now the message comes on pretty much immediately and then the battery light stays on. No off and on like before. I guess that means I don't have to hear the chimes over and over and keep clearing the message

I tried swapping out the battery (which has tested good) for the new fully charged AG battery, which just resulted in the center stack immediately shutting down along with the error message. I really don't know what to do next - I feel like I've pretty much replaced the entire charging system and had no impact on the issue.

 

[ice445]

Ok, an update on this issue (and not a positive one):

At this point I have replaced the engine wiring harness, the battery harness, and the alternator (with a new OEM unit) since last post. The only change in behavior is that now the message comes on pretty much immediately and then the battery light stays on. No off and on like before. I guess that means I don't have to hear the chimes over and over and keep clearing the message

I tried swapping out the battery (which has tested good) for the new fully charged AG battery, which just resulted in the center stack immediately shutting down along with the error message. I really don't know what to do next - I feel like I've pretty much replaced the entire charging system and had no impact on the issue.

I wonder if this is a PCM issue. Not much else left on the table

 

[RPDBlueMoon]

Ok, an update on this issue (and not a positive one):

At this point I have replaced the engine wiring harness, the battery harness, and the alternator (with a new OEM unit) since last post. The only change in behavior is that now the message comes on pretty much immediately and then the battery light stays on. No off and on like before. I guess that means I don't have to hear the chimes over and over and keep clearing the message

I tried swapping out the battery (which has tested good) for the new fully charged AG battery, which just resulted in the center stack immediately shutting down along with the error message. I really don't know what to do next - I feel like I've pretty much replaced the entire charging system and had no impact on the issue.

Did you reset your BCM when placing in your battery? I had similar issues plaguing my car for 3 years and its finally working now

 

[ChipG]

I wonder if this is a PCM issue. Not much else left on the table

When I had this issue the first time (which ended up being the alternator pigtail), the dealer did a PCM reflash to no avail. I am thinking I may be left with the unsavory option of taking it to a dealer to see if they can figure it out - though I'm concerned they won't actually diagnose, they'll just want to charge me dealer rates to throw parts at it, including any I've already replaced.

 

[ChipG]

Did you reset your BCM when placing in your battery? I had similar issues plaguing my car for 3 years and its finally working now

I did the first time I tried the AG battery, and it didn't help. Didn't do it this time, but with the OEM battery that obviously wouldn't be the problem. Was the BCM reset all you needed to make your AG happy? From my side, I want to get rid of the charging issue error before going to a next step of debugging the AG battery install, which can apparently be a little tricky as well. I just thought I'd drop it in on the chance the OEM battery was no good, but it got worse and I put the OEM battery back in.

 

[Evenmetal]

I did the first time I tried the AG battery, and it didn't help. Didn't do it this time, but with the OEM battery that obviously wouldn't be the problem. Was the BCM reset all you needed to make your AG happy? From my side, I want to get rid of the charging issue error before going to a next step of debugging the AG battery install, which can apparently be a little tricky as well. I just thought I'd drop it in on the chance the OEM battery was no good, but it got worse and I put the OEM battery back in.

You ever fix the issue? My 2017 is having the same issues. Random voltage spikes and now the car losing all power while driving.

 

[melown]

alternator seems dead^ mine died last march at 19k miles

 

[Evenmetal]

My alternator tested fine, I believe I will need to replace the entire battery harness.

 

[ChipG]

Well, yes, I did fix it, but I doubt you would want to replicate my fix. My car engine caught fire at a track event in the spring, and the rebuild included replacing all the wiring harnesses. It did work, though!

 

[WItoTX]

Well, yes, I did fix it, but I doubt you would want to replicate my fix. My car engine caught fire at a track event in the spring, and the rebuild included replacing all the wiring harnesses. It did work, though!

What caught fire?

Evenmetal, do you have a new battery? Have you done the BMS reset? Are you running an AG battery?

The AG batteries are very hit or miss in these cars. My AG was a huge miss. It now powers my trailer winch.

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