DIY upper HV pack removal

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Well-known member
Jun 20, 2015
Tallahassee, Florida
Be prepared, this pretty lengthy.

To start off, my 2012 FFE is throwing DTCs P0AA6, P1A0A, B10D7, and B1399.
P0AA6 is the Electric Battery system isolation fault, and could be caused due to the coolant leak in my case. There is visible antifreeze that has leaked out of the coolant lines.
P1A0A is more than likely caused by the BECM requesting a rapid shutdown due to P0AA6.
The latter 2 codes are just for my keyless entry, as I have yet to program the proper keys to my FFE through Forscan.

I recently purchased a 2012 FFE back in January, and have thoroughly enjoyed driving the little pocket rocket. The acceleration and handling reminds me of how it was to drive my first car, a 1994 Acura Integra, which was supremely fun to drive. Ive done a few sound/weight reduction mods, such as removing the inverter cover and sound insulation from around parts of the inverter, removed the rear seats, rear battery cover, pulled the pedestrian noise generator fuse, and the rear hidden storage cover. This just made the car obviously feel quicker, but back to the point. I took the car for a maintenance check a couple of weeks ago, as I was not only getting ready to hit 60,000 miles, but I was throwing a SSN light. The funny thing is the light was throwing itself everytime I would start the car up after letting it sit for more than 30 minutes, in which point I'd have to use my Forscan and my sisters laptop to go in and reset the DTCs, and then I could drive it as long as I wanted, without the SSN coming back on until I turned the car off and left it off for a considerable amount of time (I was also able to charge it with no problems). So, I mentioned this to the Ford Dealership, along with the DTCs I was getting, and they still charged me $115 to read the codes themselves. :(

My car was at the shop for a week as they had to wait for a person who was certified to work on EVs, and when he came to check my car, he said my battery pack had a short and needed to be replaced. They quoted me $14,000 get a "remanufactured" battery, and asked what I wanted to do next. Well, as a 22 year old student in trade school (studying to be an electrician), who barely makes that in a year (part time cashier for Publix), and someone who is in the process of converting a car to electric, I obviously was SOL and declined their offer. So I had the car towed backed to my house, and began to think about what to do next. I decided upon 3 scenarios this could go:
1.) Find a used 2017+ 33 kWh battery from a salvaged FFE (If not, look for a 2012-2016 23 kWh) and swap that in my car. Hopefully this option will cost me between $2,000 to $6000.
2.)Remove the pack entirely, and buy some modules from a wrecked Tesla, Chevy Bolt, or some other EV with higher energy density LG Chem modules. The goal is to still be around the same voltage (around 360 Volts, as too not cause harm to the other HV components). Now, I'm just hypothesizing on this option, but I think it will require a custom BMS, mounting, and some CAN work for the BMS and the other components in the car to communicate properly and not go into limp mode. Also, I could go an extra step and add in level 3 charging via Chademo. While this option would cost as much as a "re-manufactured" battery, it still could easily be a way to increase this cars range to something I could take road trips with.
3.) Just cut my loses and buy a Chevy Bolt, but that's the cowards way out. :lol:
In all seriousness, the third option is definitely the most financially safe, but I wouldn't be a true gear head/DIYer if I wasn't in it to lose money :p. Right now, Im just going with option 1 (option 2 is definitely something I plan to do after I finish my EV conversion of the Mercury Cougar, as I have no intention of selling this car no time soon).
The process for the battery removal was pretty straightforward and simple, you just need to be careful as 360 Volts DC is considered High Voltage in the automotive world (this varies in the electrician's world, depending on what that electrician is. A lineman would consider 480 low voltage and something like 11 kVs medium voltage). Using my workshop manual I got for the FFE off eBay for $10 (it's on a CD, and covers all Ford's from 2012 to 2013), and the guide a FFE owner posted on Facebook here's the link: (,-73,792 ) ,

****Before you begin, remove anything on your hands, fingers, arms, legs, head, etc. that can conduct. Things such as rings, necklaces, or anything made from copper, aluminum, silver, gold, or another conductive metal. As someone who has had a 250 Volt Nissan Leaf battery arc onto his bedroom carpet from a careless connection I made (fun times :lol) , a 360 volt battery could easily see you as a nice pathway to reach a ground source. Refer to the guide from the link I posted as you go along, here's the link again,-73,792 ****
1.) Removing the rear seats, this video can help.
2.) Remove rear weather battery cover, along with the rear cover for that hidden storage compartment, and the luggage compartment cover.
3.)Remove the seat belt plugs, you'll need to take one out anyway when removing the rear seats anyway.
4.)Pop up those hidden pockets to the sides of the rear seats, so you can pull back the carpet.
5.)Remove plastic cover for safety disconnect, and remove the upper safety disconnect. Wait 5 minutes before moving on!! (refer to page 10 of that link I got from facebook for help, or your CD guide). Remember to be careful as your still dealing with something that could kill you.
6.) To get to the lower safety disconnect, I recommend breaking the bolts for the rear passenger wheel, jacking the car up (don't forget your jackstand!), and removing the tire for easier access to the safety disconnect. The parking brake cable is going to be in front of the safety disconnect, so you'll need to move that first. There is a white retainer holding it in place, so you'll have to take that out (I basically broke mines, so be gentle). Once it's out, you'll be able to access and remove the HV safety disconnect. When that's removed, put the wheel back on, and leave the car supported by the jack stand. Wait 5 minutes before moving on!!
7.) Pop the hood and remove the cap from the coolant tank ( for degassing purposes).
8.) Jack up the Drivers rear side of the car. Remove the weather shield of for the battery, and the metal bracket the weather shield covers. (Be careful not rip the weather shield when pulling it out, as it can get caught on the metal bracket).
9.)Get a bucket and a pair of pliers. Be mindful of the HV connector next to the hoses!!! Position bucket so that when the hoses are removed, the coolant will drain into it. Remove the 2 HV coolant hoses, which should be labeled with white and red tape. The clamps are super easy to remove too, you just squeeze them in on BOTH sides of the hose and pull it off. It's probably easier to do that part by hand instead of with pliers. Once all the fluid is drained, remove the bucket fro m underneath the car, reconnect hoses, and jack down both sides of the car.


10.) Now for the fun part, be mindful of the other connections and remove the cover to the High Voltage battery junction box. It should just be one bolt holding it.
11.) Please take your time Just for fun, I checked the voltage of the two HV battery junction box connectors before removing them, just to be sure nothing was flowing through it. First, remove the bolt holding the two HV connectors (the ones that are crimped). Next you'll CAREFULLY remove the two HV connectors (I wrapped mines in electrical tape). Remove the two HV plugs to the right of the crimped connector. You'll need a flathead to LIGHTLY pry up the last step on the plug (the two HV plugs have 3 steps on the top of them to help remove them, please be careful not break them on that last step. Take your time). Remove the bolt holding the wire harness retainer (the blocky plug above the two HV plugs).
12.) Have some rags ready and disconnect the coolant hoses to the upper pack, they come off similar to the ones underneath the car. Wipe up excess coolant spilled.
13.)Now just remove the retainer bolts holding the pack to the car, for reference refer to page 29 of guide link posted.
14.) Get an engine hoist, some chain, connect it at the right points, and lift the pack out. Make sure it's balanced when lifting it out. You'll also need to twist it sideways once it's out to get it out the car. Since I was on a slight incline surface I had to remove the two light tan panels containing the the rear seat belts so I could flip the pack around.
Sit the pack somewhere safe from the weather. Make sure to cove the inlet hoses and connectors on the pack. Be sure to also pug the coolant hoses in the car, and the hole your gonna have where the battery once was.

And that's it! My situation seems to be my top pack is filled with coolant, as I noticed it leaking on the suspension when I was removing the lower battery weather shield when the car was jacked up. So I guess that's what I'm gonna replace first, and hopefully fix my SSN issue. If not, then I guess the Cougar is gonna have to wait until I can put something more energy dense in this car.
(EDIT) : The car is back working since removing the heat exchangers, coolant lines, and coolant assembly from the upper pack. I have driven over 1000+ miles now with no stop safely now light, and no problems (I still get the yellow wrench after charging, but it goes away after driving for around 10 minutes or so. Could be due to the computers noticing the two packs are different temps when charging. Speaking of that, the car handles both level 1 and level 2 charging just fine.).