Failed High Voltage Battery

[jon1eye]

The P0A0A is an interlock circuit code. From those technician comments, they found an open circuit inside BOTH High Voltage batteries. That doesn't sound likely. The working "between both upper and lower packs" would be related to the High Voltage wiring harness (orange cables and connectors). A new harness is around $1,800 retail, plus labor. The lower pack does need to be removed/ lowered to replace the harness. I just did my harness and it wasn't that hard.

How do you feel about checking it out on your own?

[FuckFordFocusEV]

I’m definitely interested. I don’t mine attempting the work.

[Anti_Climax]

Yeah, sounds like a "We ran the checks in the manual and couldn't figure out the cause. Money please"

Critical thinking and troubleshooting isn't really a part of vehicle servicing anymore, sadly.

If you do swap your harness, I will buy the bad one from you.

[FuckFordFocusEV]

I found the 2014 battery removal guide online. On page 7 it has COMPONENT LOCATION AND IDENTIFICATION section. What wiring connection are you referring to. Are we talking about #3 on the list. The High-Voltage Wiring.

[jon1eye]

I was thinking you could double check the HVIL loop to see where the open circuit is. If it's truly internal to the battery you should be able to verify that. Otherwise, it's a connector or harness issue. The wiring diagram (Cell 12, page 10) and Workshop manual 414-03A Pinpoint test step A7 should make sense and show you where to check. Essentially, the entire circuit has to be complete /no open circuit. Please forgive me, I can't seem to figure out how to upload the PPT or wiring information referenced.

[davideos]

If it is a P0A0A at the BECM, there are 5 points that you need to check. In the HV connectors, there will be 2 little pins that interface to their mating connectors. As mentioned, it is just a loop through all the HV connectors to make sure the connectors are secured.
-Check the HV disconnects. There is one behind the back seat and another by the passenger side rear tire. There was a TSB to apply some dielectric grease so the connections don't corrode. So check for that. But also make sure the pins are not bent. Then make sure that the are fully engaged. Sometimes it can look engaged but it isn't. With the disconnect engaged, pull as hard as you can to pull it out and it should not budge if it was engaged correctly. Note that there are 2 interlock connectors on these disconnects, but I think only one side is actually active.
-The 3rd interconnect is just to the right of the disconnect behind the back seat. This isn't a connector...it is just a cover; but it still has an interlock connector on it. Again, unbolt the cover and check that the pins are straight and greased.
-The next connector is at the driver-side rear tire. These can be brittle, so be careful when engaging and disengaging the clamping lever. Pull the connector back and check the interlock pins as the previous 3 connectors.
-The last one is a connector just like the previous one. It can be brittle and you need to be careful with the clamping lever. Check that the interlock pins are straight and greased.

If that doesn't work, then you might need troubleshoot the internal loop. I think it is possible but not as easy. Inside the upper battery pack where the BECM lives, I did find one end of this loop but I didn't find the other. Not much is documented inside the battery pack, but I can confirm that the one end of the BECM that I did find, the first connector in the loop is the disconnect behind the seat. It is the interlock connector on the right side that is active and then it chains to the HV cover that sits right next to it. From there, I don't know where the next connector is, but with a multimeter and some help and patience, you might be able to figure it out.

There is a similar loop at the front of the car under the hood. I'm not sure which module reports that interlock issue, but I don't think it is the BECM.

[FuckFordFocusEV]

Update.
Of. Course. Ford called back stating that the vehicle is out of warranty and that they are no programs available or recalls for the vehicle. They stated I am on my own to pay for the vehicle repairs. Now I have to see what it’s going to cost to get the vehicle out of the dealership service department.

Once I get the vehicle back I’ll see what I can diagnose and update.

[Anti_Climax]

There is an option to disable the HV interlock enforcement. You don't want to use it as a "fix" but if it works fine when that's turned off, it further isolates things.