small yellow "EV system fault warning"light (NOT large triangle)No shift into D or R

[ElectricTireShredder]

The fact that the % dropped so much seems to indicate that the contactors are closed! I believe their entire purpose is to completely isolate the HV battery when open. If they're closed, you might be able to get OBD to work.

When you disconnect the 12V, is there any voltage at the CABLES, being supplied by the car?

Assuming you tried "only":

- HV disconnect/reconnect with the 12V disconnected the whole time, then reconnected.

I would still try:

- Another 12V disconnect now.

- As NHTSA says: HV disconnect with the 12V connected, THEN disconnect 12V, reconnect HV, then reconnect 12V.

- As ratfinkharley did: HV disconnect/reconnect with the 12V connected, THEN disconnect/reconnect 12V.

If all that fails & nobody has any other ideas, I hope you've found a nearby service center with some knowledge. I hear some Bosch centers can help.

In case you'd planned on reconnecting the humidity sensor, I wouldn't bother. I unplugged mine about 5 years ago when it kept deactivating recirculate, & activating my A/C compressor without even lighting the A/C button! I've had it at the Fiat dealer for at least one software update since then & they didn't seem to notice.

[ElectricTireShredder]

I've been fixated on a solution, but I'm now wondering about the cause. It seems to have happened almost spontaneously, which is a bit unsettling.

It worked fine before charging, & failed after charging stopped. Mine once suddenly had an issue after stopping charge, presumably "infected" by the public EVSE. I wonder if there's any possibility of that having happened in this case even charging at home:

I wonder what EVSE was being used, & if there's any possibility there could have been a power outage or other source of voltage spike without protection (I keep my OEM cord plugged into a protector).

[eletricento]

The fact that the % dropped so much seems to indicate that the contactors are closed! I believe their entire purpose is to completely isolate the HV battery when open. If they're closed, you might be able to get OBD to work.

When you disconnect the 12V, is there any voltage at the CABLES, being supplied by the car? 0.19 v at cables with 12V battery disconnected. HMMMMM?

Assuming you tried "only":

- HV disconnect/reconnect with the 12V disconnected the whole time, then reconnected.

I would still try:

- Another 12V disconnect now. Done

If all that fails & nobody has any other ideas, I hope you've found a nearby service center with some knowledge. I hear some Bosch centers can help. There's a local FIAT dealer with an EV Tech

It's going to be towed to Dealer Monday unless someone steers me to a fix

[eletricento]

I've been fixated on a solution, but I'm now wondering about the cause. It seems to have happened almost spontaneously, which is a bit unsettling.

It worked fine before charging, & failed after charging stopped. Mine once suddenly had an issue after stopping charge, presumably "infected" by the public EVSE. I wonder if there's any possibility of that having happened in this case even charging at home:

I wonder what EVSE was being used, & if there's any possibility there could have been a power outage or other source of voltage spike without protection (I keep my OEM cord plugged into a protector).

​EV Busbar Level2 16 amps. Same one I've used for a couple of years. No error lights

[ElectricTireShredder]

I just remembered there are 3 fuseboxes, but I assume you already checked them all.

I'd still give OBD another try or 2 (turning off/on the dongle & the app*), & also try the other HV reset sequences from NHTSA & ratfinkharley, respectively. Just make sure to wait 5 min for "sleep" mode after connecting the 12V. For that matter, I read recently we're supposed to wait 5 min with the key out before 12V disconnect too...:

- HV disconnect with the 12V connected, THEN disconnect 12V, reconnect HV, then reconnect 12V.

- HV disconnect/reconnect with the 12V connected, THEN disconnect/reconnect 12V.



I had used the public charger that "infected" mine dozens of times prior, & used it again dozens of times later, all with only 2 problems:
- Once ABS suddenly started activating every time I braked below 7mph (fixed by 12V disconnect).
- Once I got "charging system failure", but when I got home 10 min later the OEM cord worked fine, as did that same public charger next time I used it.


*IF the contactors are staying closed, OBD should work even with the key out, at least with a good 12V connected. I'm trying to think of another way to check if the contactors are staying closed or staying open. Either way, they're not working right. With the key out & a good 12V connected, after a minute or so resting with the left door closed, the contactors should always clunk closed when opening that door, & clunk back open a minute or so later.

0.19v at the cables could just be residual from some capacitors, but the fact that it's not 14v indicates the DC-DC converter isn't running, however even with the contactors closed the DC-DC doesn't come on until you turn the key at least one click.

[eletricento]

(LAST) UPDATE: Dealer says HV Battery is bad. Still under warranty but they want to do a Buyback instead of replacing battery. Anyone else in this predicament? Is there any room for price negotiation? Do I have the option to repair it?

[ElectricTireShredder]

Thanks for the update.

It couldn't hurt to try to negotiate. You would not be the first person to repair their own. I've seen pics of one with a fully-dismantled pack to fix a coolant leak that was the only thing needed to get it running again.

The HV battery will show as "bad" with only a few bad cells. Maybe with only one bad cell. Apparently when Fiat replaces them under warranty they give you a pack made from the good cells of other "bad" packs.

Reportedly there's at least one shop in Europe that takes 500Es shipped from here which often arrive with dead cells that they either replace, or sometimes they can be "resurrected" if they were only killed by their voltage dropping too low during transport.

The HV battery will show as "bad" when it's fine but the contactors are bad, because officially they are part of the pack, & not available publicly as a separate part.

[eletricento]

The HV battery will show as "bad" when it's fine but the contactors are bad, because officially they are part of the pack, & not available publicly as a separate part.

You were correct! It was a bad Positive contactor and another DTC . See diagnosis attachedfiat diagnosis.jpg

The last line was cut off: "Per Star Center the vehicle will be bought back by FCA due to a failed HV Battery"
I guess they dont have Spell Check at my local Dealer

[ElectricTireShredder]

Dammit! You beat me to it! I'd been considering posting something like:

"Wait a sec! How likely is it that even one battery cell failed so suddenly?!"

Consider every single-cell battery you've ever used during your entire life in every flashlight, radio, TV remote, toothbrush, cellphone, laptop, or even a car's 6-cell batt, where it may SEEM like sudden failure, but in reality there was gradual undetectable degradation that just finally dropped below the threshold of functionality.

On the other hand, a mechanical device like the contactors is much more likely to fail suddenly after over 20,000 cycles such as daily use of a 2014 model.

So the bottom line is they're considering writing off a $6k+ car because of a sub-$60 part!