Yellow Wrench P0AA6, uh-oh

[electrons]

We got the Yellow Wrench recently in routine usage, and the car still works basically OK so far. Got it home anyway.
2016 Focus EV

Going to see if it is driveable to a Ford dealership for warranty repairs. The P0AA6 code seen means the high voltage system isn't isolated (resistance too low) from the low voltage system. This is a common problem and it could be a battery problem or bad relays(?).

Related: https://www.youtube.com/watch?v=hhkLNaRTQ4Y This code in a Prius indicates the current leak could be anywhere from the battery itself all the way to the electric motor!

In March 2020, I had a Yellow Wrench P0AA1, then a Red Stop-Safely-Now, a few months ago and learned a lot. They replaced the "Drive Motor Battery Pack Disconnect Switch, Disable Switch, Switch Assembly" breaker fuse, and I put on the HV battery connector splash shield since rain appeared to trigger the whole episode. Painful details at http://www.myfocuselectric.com/forum/viewtopic.php?f=15&t=4935

8-year warranty is kind of nice to have.

https://repairpal.com/obd-ii-code-p0aa6-hybrid-battery-voltage-system-isolation-fault

 

[Heima]

Here you go again. I really feel for you.
See:

https://ford.oemdtc.com/tag/p0aa6
and
https://static.nhtsa.gov/odi/tsbs/2014/SB-10056197-3051.pdf

And
Download the service manual I uploaded.
http://www.myfocuselectric.com/forum/viewtopic.php?f=14&t=4921
Install it.
Open it
Go to section 4:Electrical.
Click on section 14: Battery and Charging System
Click on section 414-03A: High Voltage Battery, Mounting and Cables
Under Diagnosis and Testing, click on High Voltage Battery, Mounting and Cables
A very long web page will load.
Type Ctrl+F to invoke search, and type P0AA6 in the search field.
Go to the second occurrence and start reading from there.
This is what the dealership needs to do to find out what is wrong, if it is not the technical service bulletin listed above.

Best of Luck!

 

[electrons]

Good info there Heima.
The 15N03 tech bulletin was for earlier models. I'd hope they put in some extra insulation or separation in the main wiring harness after they learned of the vulnerability there.

Could be anything causing this.
--- A dealership tech at least has experience working on many Hybrid cars, as its been about 15 years now that techs have been working on cars with possible P0AA6 codes, even if they have never touched a Focus Electric. Ford guides takes them through diagnostics anyway.

This Focus Electric must be driving Ford crazy with the warranty expenses. They should cut their losses and just buy them back when they fail big! I read something in another thread that the warranty cost to Ford was $33,000 on somebody's Focus Electric. Just extreme.

Curious to know if all the new Ford Mach-E's will visit the repair bays often. I wouldn't be surprised if Ford takes another bath on that one too. (Ford shoud only sell the high-profit F-150 and lux SUVs and cut their losses.)

 

[electrons]

Just got the car back. They say it was the Air Conditioner assembly that had too little resistance at some point in the recennt past, triggering P0AA6 Yellow Wrench, so I had to pay $174 for diagnostics, not on the 8-year warranty.

I haven't had the Yellow Wrench appear enroute back and forth to the dealership, and they said if was never an active (current) fault when they diagnosed it. They cleared out the history and told me they could replace the Air Conditioner assembly for $3,600, and I declined.

We're just going to keep driving it. The Air Conditioner works. I can't see spending $3,600 for an intermittent P0AA6 fault. Maybe it will be OK. Speculation leads me to think the AC made some water condensation which temporarily got between and power and ground a little, lowering the resistance and making it fail the P0AA6 test.

 

[electrons]

As I said in my previous post, they proposed $3,600 to replace the AC Compressor, a bolt-on part accessible from underneath that has an internal electric motor paired with a compressor. RockAuto has the CV6Z19703G compressor for $1,415, while dealerships often charge around $2,400 for the same part.

It looks like it can be changed by disconnecting the refrigerant lines, orange electrical connector, and 3 mounting bolts. I think a normal mechanic shop could unplug & unbolt the old one, bolt & plug in the new one, and re-charge the A/C system as necessary. Mine is still working, but it may be pesky.

I'll bet I can get the big A/C compressor, and pay labor to a mechanic accustomed to playing with the R134a lines , for $1,400 + $300 = $1,700 total, instead of a dealer's $3,600 !

Might have to check the Service Manual to see what kind of compressor oil it takes, as I think it could be unique to this animal, not typical.
Also to make sure the main HV battery disconnect procedure de-energizes the system properly, that too.

 

[Heima]

You really should get yourself a good dual speed OBDII interface and Forscan. You could do your own diagnostics and resetting of codes. I use a OBDLink MX+ and a windows 10 tablet. Its very convenient. Especially when you wanna see different system parameters.

An isolation fault inside of an air conditioner is an odd thing. Your thinking of a little moisture in the connector might be the truth. I believe the connector is at the junction box under the big rubber 'engine' cover. You could pull the interlock from behind the back seat, then pull the rubber cover, and then check the connector. It is the center one of the three on the passenger side of the junction box. You could use an ohmmeter to check the resistance of each of the two high voltage terminals to 12V battery negative.

 

[electrons]

You really should get yourself a good dual speed OBDII interface and Forscan.

I've got an old ScanGaugeII for quick easy readings, and an ELM327 "BAFX Products OBDII Diagnostic Interface" (amazon.com) used to bluetooth to my android (LG G7 ThinQ) phone to run the free versions of 2 apps, Torque Lite & FORScan Lite. I recommend all those products.

Oddly, the ScanGaugeII and Torque Lite would NOT read the Focus Electric, while the FORScan did, to get the P0AA6 reading. !? FORScan came thru at least. They all work on BMW, Chevy, & other Fords, yet something was different on our Focus Electric.

I use a OBDLink MX+ and a windows 10 tablet. Its very convenient. Especially when you wanna see different system parameters.

I've been mostly cheap about it, just getting the free 'Lite' versions of phone apps.
Torque Lite is great for creating a visual display (round gauges or digital) on the dashboard to look at pressures, temperatures, etc., which was cool on a C-Max I used to have.

An isolation fault inside of an air conditioner is an odd thing. Your thinking of a little moisture in the connector might be the truth. I believe the connector is at the junction box under the big rubber 'engine' cover. You could pull the interlock from behind the back seat, then pull the rubber cover, and then check the connector. It is the center one of the three on the passenger side of the junction box. You could use an ohmmeter to check the resistance of each of the two high voltage terminals to 12V battery negative.

You're right, the A/C power & signals plug into the top junction box. I noticed it's all similar to what you see on C-Max Hybrids, which makes sense since it can't run a belt pulley off a gas engine shaft for a C-Max hybrid nor a Focus Electric.

 

[scottt]

Might try calling Ford. What's the worst they can say?

When my grandparents passed away I purchased my grandfather's PT Cruiser GT from the estate. About 4 months after the 3 year warranty expired, the power steering pump started to leak quite a bit. Was going to be about $1600 to fix, as most of the front end of the car had to be taken apart to get to it. I called Chrysler and when they got back to me they said if I paid $150 they'd take care of the rest. Needless to say I jumped on it.

As I always tell my younger co-workers, never hurts to ask.

 

[electrons]

It's an electrical Gremlin. Appeared twice early on, now several trips later, no problem with the AirConditioner being a current path from high voltage to ground, no more Yellow Warnings. .... for now.....

 

[Heima]

I always liked the door handles on AMC vehicles. Simple, yet elegant.
My family had a 74 Matador wagon. I called it the blue whale. Tried to convince my mother that the rising gas prices at the time were going to continue, and instead buy the Volvo wagon she was also considering. But American loyalty to large vehicles won over, and she regretted it as long as we owned it. I think it was 14 miles a gallon.