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Dead H battery

7K views 13 replies 4 participants last post by  FordService 
#1 ·
2012 FEH Ltd. bought new Feb 2012, about 50K on the clock.

For several months I have been getting a "Check Brake System" message every few weeks. A restart clears the message, only to re-occur a couple weeks later. No functionality problems with the brakes. No difference in how the hybrid system has been working since day one. So to the FMC dealer it went. The dealer recommended that the vacuum hose assembly be replaced. By mistake, an incorrect vac hose assembly (for a non-hybrid, but was a FoMoCo part) was installed by an independent mechanic. This did not correct the problem, it still threw a code. As before, the brakes still worked perfectly. Back to the FMC dealer it went. The dealer replaced the vacuum hose assembly with the correct one for a hybrid, as well as the power brake unit. The dealer then could not calibrate. The dealer now tells me the hybrid battery is completely dead. FMC is replacing the battery under warranty, or so I've been told. We are now waiting for the new battery so they can install, then calibrate, then try to discover the reason why the battery died.

About 2 months prior to taking it to the dealer, and about 2 months AFTER I got the first "Check Brake System" message, the regular 12V battery died. I observed a VERY corroded cable clamp at the positive terminal, so I cleaned it up with some baking soda/water solution. The cable itself looked slightly corroded right where the clamp is attached, but I didn't replace it. I then installed a new battery. Everything seemed fine. But still kept getting the brake message.

Could there be any connection (pardon the pun) between the 12V battery dying and the hybrid battery dying?

Thanks in advance for any guidance.
 
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#2 ·
I find it odd that they say the hybrid battery completely died. Especially for a 2012 that's odd. Hybrid batteries are hard to deplete all the energy from them. Don't quote me on that but that's just my take on it. Maybe one of the hybrid owners will chime in on this.
 
#3 ·
The two systems aren't really related. The 12V battery is charged by the HV battery by way of a voltage converter. In that sense, if the HV is having problems, then it is possible that the 12V system won't charge properly. The CHECK BRAKE SYSTEM message can be triggered by a weak 12V battery. I got that message on mine when my 12v cables were loose. I think your HV failure caused the 12V failure, not the other way around. A HV failure is VERY rare. Yours would only be the second I've ever heard of. What was more common was corrosion in the connectors going into the HV battery pack. I'm glad that Ford is replacing it for you under warranty though.
 
#4 ·
Thanks for the info Jay.

The HV battery was delivered yesterday (250 pounds, shipped truck freight!), the dealer tech put it in this morning (with a forklift) and everything is working correctly. I picked up the car tonight and it all seems fine. Ford paid the total cost of the battery, freight and installation. List on the battery is just under $10K! From new (Feb 2012) I have an 8 year 100,000 mile warranty, which continues with the new HV battery.

I asked the service writer about the HV battery going dead, he's never heard of one doing that.

Now I wonder if I should replace the slightly corroded negative 12V battery cable, and whether the dealer should do that under warranty.

I would appreciate your thoughts on that issue Jay.
 
#6 ·
I will address the cable issue with the dealer and see what transpires. A correction: the cable is the negative cable, not the positive.

All has been working fine, until yesterday. While accelerating on a 55 mph hwy, going about 50 (gas engine engaged), the car shuddered, recovered, then stumbled again, then died. I was able to coast to a safe spot. No gas engine, no electric propulsion either, but gauges were working and electrical system seemed OK otherwise. So I turned off the ignition, then restarted, and all was fine. I've driven it about 50 miles since without a problem.

A very weird anomaly occurred during this episode: the rear glass washer pump squirted fluid, just as if I had turned it on for a few seconds. Very strange.

I think there may be other deeper issues and I should return it to the dealer to see if it threw a code and to get the cable replaced.
 
#7 ·
Dealer service writer has told me that the neg battery cable needs to be replaced, it is corroded at every connection, which I already knew, and it's is not covered under warranty. What's another $600 bucks between friends, right?

The service guy experienced some strange stuff too: once started he couldn't get it to run, then couldn't start it at all. Both times the rear glass washer pump puked a bunch of fluid.

My FEH is possessed.
 
#8 ·
More on my possessed HEV.

Dealer replaced the negative battery cable, cleaned all corrosion, and took a test drive, which went fine. Upon starting the vehicle again, it wouldn't start and the rear glass washer pump puked a bunch of fluid again.

The dealer is out of ideas and has contacted the Ford Hotline (Ford Engineering) for some guidance.

Not happy.
 
#9 ·
The latest updates.

The Ford dealer service tech was instructed by Ford Engineering to do a pinpoint test, which indicated a faulty module at the HV battery, I guess this is the electrical interface between the battery and the rest of the electrical system. Quoted price to replace the module is $700+, on top of the $600 for the 12V battery cable.

Later the service writer called and said the tech noticed that the module connections were loose, so he got it all connected properly, and that seems to have cleared the problem with the module. :roll: They cannot get the vehicle to malfunction as before, so maybe this solved that problem. They want to keep the car for a few more days and see if it continues to operate correctly.

I have asked the service writer and tech to go online and research the problems I am having, so they can build a case to allow Ford corporate to consider these electical problems to be caused by the dead HV battery. I have read quite a few threads about an Escape Hybrid having almost identical issues.

During this whole episode, the only fault warning I got was "Check Brake System". The info center always indicated "Electrical System OK". NEVER any indication that the HV battery was losing charge or was depleted.

I now question whether the PB booster and vacuum hose assembly were truly defective. I now think the HV battery likely caused the 12V battery and cable to corrode, leading to catastrophic failure.

If anyone has further insight or advice I would be grateful to hear it.
 
#10 ·
Grady said:
Later the service writer called and said the tech noticed that the module connections were loose, so he got it all connected properly, and that seems to have cleared the problem with the module. :roll: They cannot get the vehicle to malfunction as before, so maybe this solved that problem. They want to keep the car for a few more days and see if it continues to operate correctly...
Hello Grady,

Thanks for the update, and please keep me posted on the result. If further help is needed, just send over the mileage, and I'll be happy to check my resources at that time! :)

Tricia
 
#11 ·
Thanks for your reply Tricia. I appreciate the call from your Ford Hybrid Engineer before picking up my car. I have the car back and I have driven it about 200 miles. So far the HV battery seems to be working as it should.

I was told the service tech did some investigating and while examining a module (?) behind the trim at the driver side D pillar, he found the screw holding it in place was cross-threaded, and it's obviously been that way since the car was assembled. I was told that his opinion is the module (or whatever it is) was therefore not properly grounded, though I am unclear what effect that had on the problem(s) I experienced. I could not get a concise answer to that question.

Also, after getting the car home, I opened the hood and noticed some parts were loose. The air cleaner plenum was loose because a screw holding it to the inner fender was gone. A bigger problem was the battery hold down clamp at the back of the 12V battery was gone as well, so the battery was loose. I returned the car to the dealer and the service writer had the service tech replaced those parts while I waited.

If there are any further issues I will post them here, as well as call you or Dan for advice.
 
#12 ·
Grady said:
Thanks for your reply Tricia. I appreciate the call from your Ford Hybrid Engineer before picking up my car. I have the car back and I have driven it about 200 miles. So far the HV battery seems to be working as it should...
Hello Grady,

Thanks for keeping me posted, and I'm glad to learn that your dealer resolved your concerns. Let me document your dealer experience. Please PM your full name, VIN, mileage, dealer, and best daytime phone number. I'll ensure it's noted.

Have a wonderful day! :yes:

Tricia
 
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