abeln2672
Posts: 17
Joined: Sat Jul 20, 2019 12:52 pm

ACC/Front Collision/Pedestrian systems not working on 2014 Rex

Hi all! 2014 Rex started giving me errors yesterday on all systems related to the front camera: ACC, pedestrian detection, and front collision warning. I've driven the car multiple times since then and the errors always come back within the first minute of turning it on. After googling and posting to the FB group, I got some suggestions to clean the windshield, check for condensation in the camera assembly, disconnect the 12v, and check motor mounts, all of which I did, but no luck. I also tried locating a fuse for the camera system to see if it was blown, but I couldn't figure out which controls it. My next step would be paying for the full version of Bimmerlink to pull any error codes, but I was wondering if anyone else has experienced this and if so what the problem was. The real drag about this is in picking up my new car tomorrow (2017 Ioniq Electric) and have an outstanding offer from Carvana for the i3. So I was literally days away from selling it, but I now have a seemingly major malfunction. Any help is appreciated!
frictioncircle
Posts: 299
Joined: Fri Nov 25, 2016 11:23 pm
Location: USA West Coast

Re: ACC/Front Collision/Pedestrian systems not working on 2014 Rex

abeln2672 –

The behavior you describe sounds like your 12V auxiliary battery has expired. Fixing the situation isn't difficult: buy a new 12V battery, pre-charge and install it, then register it.

As you're on the verge of turning your i3 in to Carvana (sad face) the above may be more time that you want to invest, so letting Carvana deal with it may be the least stressful way to go.

That said, if you want to fix the issue before turning it in to Carvana, buy an AUX18L battery from Remy (US$140).

Once it arrives, use a battery charger to make sure it's fully charged before installation.

After installation, register the battery to the car. Registration lets the car know that it has a new battery so it can apply a charging regimen appropriate for a new battery as opposed to one that's seven years old. Battery registration is something that you can do with a mobile app like BimmerLink. To use BimmerLink you'll need to purchase the app (US$36) plus a Bluetooth->OBD-II adapter (US$42).

All of the above comes to about $220 (plus sales tax) which is still more economical than taking your i3 to a dealer for this service. A US dealer will charge $400-$600 for 12V battery service.
abeln2672
Posts: 17
Joined: Sat Jul 20, 2019 12:52 pm

Re: ACC/Front Collision/Pedestrian systems not working on 2014 Rex

Thanks so much for the quick response! The battery was actually the first thing I thought of as well having read many stories of strange error messages being randomly thrown because of a failing battery. Is there any real way to check that without just going ahead and replacing it? For example, I wonder if I hooked up a multimeter to check the voltage of the battery whether that would definitively tell me it's failing or not. I bought the car used about 2 years ago and was told the battery had recently been changed, so I'm guessing it's no older than two and a half years or so. I think I can check the manufactured date without removing the battery so I might start there.
alohart
Posts: 2550
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: ACC/Front Collision/Pedestrian systems not working on 2014 Rex

abeln2672 wrote: Sat Jan 22, 2022 9:34 amFor example, I wonder if I hooked up a multimeter to check the voltage of the battery whether that would definitively tell me it's failing or not.
If you have a 12 V battery charger, turn off the high-voltage disconnect and fully charge the 12 V battery. Then measure its resting voltage several hours after charging has completed. If it's above 12.6 V, the errors should go away if low 12 V system voltage was to blame.

You must wait for the high-voltage system to shut down before measuring the 12 V battery's voltage. To get a good resting voltage, I open the frunk after parking for the night and measure the battery's voltage the following morning before unlocking the doors. If the frunk is completely closed, opening it would start the high-voltage system, so don't close the frunk all the way. I recently replaced the original 12 V battery in our 2014 i3 after the resting voltage of its battery was only 12.26 V after fully charging it the previous day with a battery charger.
Aloha,
Art

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abeln2672
Posts: 17
Joined: Sat Jul 20, 2019 12:52 pm

Re: ACC/Front Collision/Pedestrian systems not working on 2014 Rex

Tested the battery just now and it came up over 13 volts, so I guess that's not the problem. After that I broke down and paid to get error code access on the bimmer link app and pulled a lot but the one that seems most relevant and is still present is 800AC4, "camera calibration failed ". Haven't been able to find too much out about that online, but I'll keep playing around with that and maybe try to clear the code and see if it comes back. Unfortunately it seems like this might end up being when I have to take it in for which is a real drag considering I was days away from selling the car. It's been good to me during my time though, so I guess I can't complain too much LOL...

Edit to say I opened the housing around the cameras and the bottom one (sensor?) was just hanging down, apparently having come free of the adhesive that attached it to the windshield. I know one can get a hold of ISTA and recalibrate it, but the learning curve and time investment there seems pretty steep. I'll probably call a shop this week to see if they can attach and calibrate it. Hopefully that's the only problem!
abeln2672
Posts: 17
Joined: Sat Jul 20, 2019 12:52 pm

Re: ACC/Front Collision/Pedestrian systems not working on 2014 Rex

Just updating for posterity. Independent shop couldn't figure it out so it went to BMW who said it just needed a recalibration. They noted the windshield had been replaced at some point and could've been the issue, but I've been driving it for two years with that windshield (replaced before I owned it) and not had a problem. So I have no clue. Anyway, they charged only their $188 diagnostic fee since they spent less than an hour with it, so I felt quite lucky. Carvana is coming to get it Monday.
frictioncircle
Posts: 299
Joined: Fri Nov 25, 2016 11:23 pm
Location: USA West Coast

Re: ACC/Front Collision/Pedestrian systems not working on 2014 Rex

abeIn2672 –

Thank you for sharing the outcome of your situation – it will be helpful for future owners!

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