Jump to content
Do Not Sell My Personal Information


Ford C-max mk2 battery drain - bluetooth module fault?


jura7035
 Share

Recommended Posts

Reposted from Ford C-max Club forum.

I should state from the outset that I am not a mechanic and that this is my first post.

I have owned a Ford C-Max Titanium 2011 car for 4 years now.
Up until July 2019, my car has only shown minor annoying electrical issues. E.g. intermittent 'Power Steering malfunction' during engine start-up causing the steering wheel to lock up (the only way I have found to unlock the steering wheel is to turn off and restart the engine then quickly applying slight pressure on the wheel to unlock it).
I have never had a 'Low battery warning' message appear on the dash.

Here's my battery drain story (sorry if it's a bit long).

My brother-in-law borrowed my car for 3 weeks during July 2019 when he came on holiday to the UK with his family.
Within one week, the car's battery had drained. He managed to jump-start the car for the next stage of his tour around the UK, but within 2 days the battery had drained again. He trickle charged the battery, but 4 days later it drained. At this point, he took the car to a garage who told him that the battery was faulty and needed replaced. During my ownership, the battery had not been replaced so I agreed for a new battery to be installed. (I now believe that there had not actually been any problem with the car battery.)
This appeared to fix the issue because my brother-in-law didn't experience the battery drain issue during the last week of his UK tour.
He handed the car back to me and I took it out for a 50 mile run that day.

Two weeks later, I discovered that the battery had drained.

At this point, I started trawling the internet for information about C-max battery drain issues but my initial trawl revealed nothing.
I checked the battery voltage and found that it was down at ~3V.
I trickle charged the battery, then I confirmed that the battery voltage reading was ~12.7V.
I started the engine and confirmed that the alternator was charging the battery correctly (I got a reading of ~13.5V).  
I then checked for battery current draw by placing my meter in series with the battery and found a parasitic draw of 170mA, so started pulling fuses/relays to see if the draw disappeared. I since found out that I was wasting my time with this fuse pulling exercise. I took the car to my garage who reported that they could only see ~20mA current draw.  They explained that my 170mA reading was actually the current draw when some of the car's electrics were still active, and I needed to wait up to 40 minutes for the car to enter its 'quiet' mode.
Anyway, my garage could not detect any issues with the car and declared the battery to be in good condition, so I took the car back home.

One week later, the battery drained.

I trickle charged the battery and drove the car back to my garage but they still found nothing wrong.
However they did say that another mechanic had told them that he had enountered two C-max cars which had bad radio modules, and disconnecting the car head unit fixed the battery drain issue. So garage disconnected the head unit from my car.

3 weeks later, the battery had not drained.
I then thought about whether a fault in the head unit made sense. My gut feeling was that it did not.
So I continued to trawl the internet and then I found a few discussions about faulty bluetooth modules. One discussion in particular suggested debonding all bluetooth devices from the car and disabling bluetooth:
https://www.kugaownersclub.co.uk/threads/mk2-kuga-2014-battery-drain.16499/
So I reconnected the head unit and checked which devices had been bonded to my car, only to discover that my brother-in-law had bonded an iPad to it. I had found a smoking gun! I debonded all devices and turned bluetooth off, and the battery drain issue disappeared!

It took me 2 months to get to this point.

So I thought that the most likely possibility for the battery drain issue was that the iPad was not on the list of approved bluetooth devices for my C-max's firmware and that somehow it caused my bluetooth module to randomly turn on, waking the car's CAN-Bus up which pulled a large current from the battery.

I have left the bluetooth turned off ever since and I have had no more battery drain issues ... until March 2020.

Last week, I took my car out during the day on a 14 mile run, stopping only once. I had no issues until I tried to lock the car with my key fob on my return. The wing mirrors automatically fold in when I lock the car, but they didn't fold in this time. I unlocked the car and the wing mirrors folded in. Obviously the car had become confused. So I locked the car again, but the wing mirrors folded out. I checked that the car alarm led was flashing on the car's display and decided to leave the car overnight with the wing mirrors sticking out. In retrospect, I should have gone back into the car and done a 'System Check' on the car's menu to see if the car reported any errors.
The next morning, I unlocked the car with the fob and the wing mirrors stayed out. I locked the car and the mirrors folded in. Issue fixed, or so I thought.
(As an aside, there doesn't seems to be any way to stop the wing mirrors folding in when I lock my car. Maybe someone on this forum knows differently?)

3 days later, the car battery had drained.

Now I don't know if my bluetooth module, the wing mirror electrical system, or another electrical module/circuit is causing the battery to drain.
I have trickle charged the battery again, taken my car for a 30 mile run, and the car seems to be working as it should.
The battery voltage is OK, giving ~12.7V with engine off and ~13.5V with engine running.
I now plan to follow this battery drain analysis guide to try and isolate the faulty circuit:
https://www.youtube.com/watch?v=lRcj1fQcWwU
(If there is a better guide out there, I would appreciate if someone could let me know.)

From what I have gleaned so far, most of the car's electrical modules communicate via CAN-Bus.
If any connected module fails, it can cause the CAN-Bus to turn on, which kicks some additional electrical systems into life, and causes the battery to drain quickly.

So finally, to my main question.
If there is an intermittent parasitic draw issue with my car, are there any diagnostic logging tools that allow intermittent faulty modules to be easily identified?
E.g. a diagnostic tool that logs the communication on the CAN-Bus over a long period of time (say 24 hours) when the car is in 'quiet' mode, and hence will identify any module that turns on when it shouldn't.

I intend to post an update on my fault diagnosis journey in a couple of weeks.

Link to comment
Share on other sites


I think you have posted it here again.

Link to comment
Share on other sites

Hmm ... so I have. I posted it under 'General Ford related Discussions' but it seems to have automatically appeared in the 'Ford C-max Club' forum.

A newbie mistake, methinks.

Link to comment
Share on other sites

1 hour ago, jura7035 said:

Hmm ... so I have. I posted it under 'General Ford related Discussions' but it seems to have automatically appeared in the 'Ford C-max Club' forum.

A newbie mistake, methinks.

We've all done it😀

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share




×
×
  • Create New...

Forums


News


Membership