Welp, it's dead...

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Active member
Mar 15, 2022
Our FFE was unable to start earlier this week, so we towed it to the dealer. I just now heard back from them. It needs $3.5k in repairs (water leak in battery harness), and that repair might lead to the discovery of any number of systems which have also shorted out as a result of the leak. It has 105k miles on it, so sadly, it's time to say goodbye.

I'm looking for any guidance on how best to recoup some expenses here. The battery was replaced under warranty in 2020, so I know it has value. I'm just not sure what direction to go here to mitigate this financial gut-punch.

Any advice would be greatly appreciated. Thank you.

EDIT: I should specify, I'm located in Los Angeles, in case that makes a difference for potential battery buyers.

EDIT 2: And to clarify, this was not the dreaded FFE battery coolant leak.
I'm not sure how "water leak in the battery harness" differs from the coolant leak issue seen before - can you elaborate?

If it's possible for you to hold on to it yourself, you can easily part it out for far more than any scrap yard will offer.

Battery, most of the modules, motor, on board charger, AC compressor - when you're all done you have a rolling chassis that you can probably sell for what you would have gotten for the whole thing anyway. If course you can sell that to someone that ends up wreaking theirs for even more.
I cannot help but think that a "Water leak in the battery harness" is a lame catch-all phrase for "we have no freaking clue what is wrong, so we pulled something that sounds serious out of our ass." If they are that certain of the cause, they should be able to tell you which harness needs to be replaced.

I am thinking that there is either an isolation fault, or an HVIL fault. And the dealership doesn't know how to deal with it. If you can provide the actual DTCs we could look them up and see what is going on.

Being an LA car, corrosion from water and mud is probably unlikely. However with recent rains, maybe water got in where it should not have, and it is causing an isolation fault. The 3 high voltage connectors at the LH rear wheel and the high voltage disconnect at the RH rear wheel are coming to mind. Following that train of thought, there is the high voltage connectors on the charger under the car as well.

Considering the car got the new pack a couple years ago, maybe somebody didn't button it all up correctly back then.
Alright, so more details. This is the harness: PART # CM5Z14A318D

He says the brackets that secure the harness to the vehicle have a rubber component that dried/degraded over time, which left the harness exposed to water. It does kinda make sense, since we were having a ridiculously rainy week in LA when this happened. If something was already vulnerable to water damage, this was definitely the week it was going to happen.
I was able to find that assembly on eBay for about $1000. However, it kind of looks like it might be the one that connects near the driver-side rear tire. If the problem is at that connection point, there is a TSB for that where Ford will (or used to) fix that for free. May have just been the battery side, not sure. But they would also install a shield to protect those connections.

I've had my battery replaced too, and those connectors get brittle over time. When I last had an issue with my car, the dealer actually broke my connector handle as well as the mating portion on the battery. I was able to make some modifications to secure and hold the connector in place and it has been holding for 4 or 5 months now.

Anyway, I'd ask the Ford Dealer if there are any TSBs related to the issue that might cover the cost of the repair. Sorry I don't have the reference number. I just came across this when I was troubleshooting my issue last year.
In that context, that verbiage makes sense.

You can get all of those harness connectors by themselves from mouser or digikey and they can actually be disassembled. The socket side may not be as easy to replace by they should also be removable if you had to.

Might be worth pulling apart to look at them. You might be able to clean up what's there.

I think there was also a disconnect that had issues, that might be the TSB that was mentioned.
And this is what the part looks like:
It looks to be almost all of the high voltage cables together.

I just checked the service manual for the installation of the harness, and nowhere does the harness penetrate an HV battery enclosure.
The design of the harness is such that water is not going to get into the cabling, but maybe a connector. BUT, the connectors on both sides, the males and the females, should both be water proof.

I really think that a good thorough check of all HV connectors, making sure that they are clean and dry, might just resolve the problem. tIf you go that route, only use 70%+ isopropyl alcohol for cleaning. De-oxit, contact cleaner, dilectric grease, etc can leave a residue that can become problematic.

There was a TSB for the external connectors on the lower pack. They used an aluminum interface block to mount the connectors to the lower pack enclosure. When exposed to salt, the aluminum corroded and expanded, opening a gap between the high voltage connectors and the aluminum block. This allowed moisture and water to enter into the pack, and cause a loss of isolation. The bulletin has the service tech clean the connectors, check the gap width, and apply a sealant. Even an acceptable gap width and sealant might permit water to enter the pack if the connectors are just submerged.
Looked it up - the connectors on the SOBDM are from the Aptiv HV280 series and have pins and seals available as replaceable parts.

The high current ones are from their HV AK line and should also be serviceable.

This should have most, if not all, of them:


That should cover pretty much everything on the battery harness.