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Discussion Starter #1
30-second 12V disconnect often corrects 500e issues, but when it doesn't, would HV disconnect help?

If so, can you just unplug the orange connector under the rear seat & plug it back in?
 

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Was wondering about this recently. A friend bought a used 500e, apparently with a dead 12v. Can’t pull key out, won’t go into gear, weird flashing screens.
Even after unplugging the 12v for a while and then reconnecting it and plugging it to a portable jump charger the car remained unable to select gear, though we were able to remove the key and most error messages went away. More importantly we were able to get a bt Obd plug going, and that allowed me to clear faults from the alfaobd app so a few secs later the car was drivable again and error free. So I’d try that before unplugging hv batt
 

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That one has me puzzled. I can understand disconnecting/replacing the 12V. What condition would unplugging the HV batt fix... maybe turn off the DC/DC converter?
 

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Discussion Starter #4 (Edited)
I just wondered if HV disconnect could help either of 2 recent threads ("L2 EVSE charge failure" & "2015 5003 Limited Power Mode") where owners tried 12V disconnect, & charger reboot, to no avail. I don't think they've tried OBD clearing, but the "Limited Power" owner has ordered one to try that. I haven't got one yet either,
 

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My 12V has died on my 500e 2016 while away on a trip... I've recharged the 12V and now car comes up with "limited power mode" turtle and a stored warning which says "service electric vehicle system".

Here are some possibilities I've found on forums:
  • disconnect the 12V positive for 60 seconds and pump the brakes - did nothing ❌
  • disconnect the 12V negative for 15 minutes and hold the brakes down for 5 minutes - did nothing ❌
  • turn on and off 5 times - did nothing ❌
  • disconnect the HV - how do you access the orange connector? - have not tried ?‍♂
  • replace the 12V battery - have not tried ?‍♂
  • order and OBD and reset the code - have not tried ?‍♂
  • call Fiat, tow to them, have them fix - have not tried ?‍♂
Any other ideas or opinions on what to do??
 

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I would only disconnect the HV as a last resort - or at least make sure you fully understand what you are getting into.
What voltage is your 12 V reading? I would get a new 12 Volt battery as the first step. Your's is about 4 years old and probably needs replacement anyway.

I seem to recall the turning on off thing is more like 10 times and not 5. Not sure. Also not sure about resetting codes, but worth a try.
 

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Discussion Starter #7
I would only disconnect the HV as a last resort
Absolutely! That one should probably be moved to the very bottom of the list, but to access the orange connector just pull straight up on the little webbing strap* buried behind & between the two center rear seat belt sockets. *very much like the one you use to pull the hatch down.

After my older posts above, someone had success with what I'm now calling a "1-weekend 12-V disconnect": They were going for an hour or 2 & then ended up leaving it off for a day or 2.

When you cycle the key off, make sure you wait for the speedo screen to go fully black. I have had that work after 3 or 4 tries, but it's easy & can't hurt to try 10, before bothering to disconnect the 12V.

Disconnecting positive or negative makes no difference EXCEPT that the negative:
  • Is easier to access at the front with no separate cover.
  • Can't short out onto anything with the wrench.
  • Has a horizontal bolt & no plastic (unlike the positive)
Just charging the car, or turning the key to "on" or "start" will charge the 12V. Then if it will drive, call your favorite auto parts store to see if they do free 12V testing (most do) but make them show you the voltage. If it's 12V (like mine that drives fine) or more, then I would try a weekend 12V disconnect or HV discharge to zero, whichever is easiest, & if one doesn't work, try the other.
 

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I left the old 12V disconnected overnight. Bought a new 12V and installed this morning (Maxx-H5). Same error.
Now tried turning on and off 10+ times... hoping for different results. Unless I'm mistaken, that's the definition of insanity.

No change in status. Now leaving the 12V disconnected as it seems the new battery would only go dead under these conditions.

Guess I will call to see about towing this pile of metal 30 miles to see if they can reset it. They say the next actual service appointment is a week out but towed in vehicle may be able to be looked at earlier :/
 

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Discussion Starter #9
I can't think of any reason for the 12V to be drained, since your only symptoms are a "limited power mode" turtle and a stored warning which says "service electric vehicle system". It can't hurt to disconnect it though, but maybe one night wasn't quite enough. I think I saw 30 hours worked for someone.

I did see a vid reporting driving fine in "turtle" mode, but either way it seems like discharge to 0% would be the next thing to try, with immediate non-stop recharge to 100%, preferably on L2.
 

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The 12V died after sitting undriven only for a few days and seems to have initiated the turtle and service warning. A battery tender may be the only way to prevent this in the future when the car is not being driven?

I just used my friends $10 Bluetooth OBD2 diagnostic scanner and the AlfaOBD android demo app to find and reset the faults. Codes are gone and the car runs now ?
 

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Discussion Starter #11
Since your codes are gone, a worn out 2016 12V was likely the cause.

It probably died originally just from old age. 3-4 years is not uncommon, especially if it's got an average amount of miles or more, because the more you charge, the more heat you inflict on the 12V from the hot onboard charger right beside it. My buddy's 2014's 12V died in Sept 2018.

The 12V gets charged the entire time the key is on, AND the entire time the car is charging. That helps even my fairly unhealthy 4.5-yr-old 12V work fine after 5 days parked unplugged (probably more, but I haven't recently gone THAT long without driving).
 

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I left the old 12V disconnected overnight. Bought a new 12V and installed this morning (Maxx-H5). Same error.
Now tried turning on and off 10+ times... hoping for different results. Unless I'm mistaken, that's the definition of insanity.

No change in status. Now leaving the 12V disconnected as it seems the new battery would only go dead under these conditions.

Guess I will call to see about towing this pile of metal 30 miles to see if they can reset it. They say the next actual service appointment is a week out but towed in vehicle may be able to be looked at earlier :/
Hello MarkS,
If you do end up getting the vehicle towed please send us a PM. We would like to have this documented and have a case escalated in your behalf so a Case Specialist can work with your dealer to help find a potential solution.
Laura
FiatCares
 

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Thanks for all the replies on this btw...
@Shredder, the codes are gone because I reset them with the AlfaOBD app. Have yet to see if they'll return. Now putting a battery charger on the 12V whenever I leave it parked for more than a day :/

@Laura, your message is much appreciated. A "service propulsion system" did come up with a red triangle but has since disappeared. Doesn't look like it'll need a tow but I'm debating weather to set up a service appointment for a condition, and codes, that no longer exist.

It's a fun car to drive and perfect size for easy parking. When the 12V goes low, error codes start to trigger and don't seem to easily reset :/
 

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Discussion Starter #15
Right. Last year I left my own 5.5-year-old 12V for at least 1 full week & it was fine. It's now 6.5 years old & last week I left it for 5 days & it was fine.
 

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Discussion Starter #16
If a new 12v goes dead when parked for a week, over 99.9% chance there's something wrong with your car (<0.1% chance the new batt is bad) BUT you'll never know unless you try. Obviously have a jumpstart handy just in case, or do it somewhere you can recharge the 12V. I'm not sure if the car will charge (which also charges the 12v) if there's no power from the 12v.
 

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The 12V died after sitting undriven only for a few days and seems to have initiated the turtle and service warning. A battery tender may be the only way to prevent this in the future when the car is not being driven?

I just used my friends $10 Bluetooth OBD2 diagnostic scanner and the AlfaOBD android demo app to find and reset the faults. Codes are gone and the car runs now ?
Was wondering about this recently. A friend bought a used 500e, apparently with a dead 12v. Can’t pull key out, won’t go into gear, weird flashing screens.
Even after unplugging the 12v for a while and then reconnecting it and plugging it to a portable jump charger the car remained unable to select gear, though we were able to remove the key and most error messages went away. More importantly we were able to get a bt Obd plug going, and that allowed me to clear faults from the alfaobd app so a few secs later the car was drivable again and error free. So I’d try that before unplugging hv batt
Have the same problem
Downloaded the alfa obd but can't find where to delete the codes
 

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Have the same problem
Downloaded the alfa obd but can't find where to delete the codes
Were you able to connect to the bt reader? If yes, you’ll need to select the right module to connect to, then clear codes. Don’t recall the exact wording but it should be obvious. It’s however not like your typical car where you just clear all codes and then get a nice confirmation. If no luck, post back and I can go get more specifics.
 
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