Brake System Warning light (yellow)

[Wavebender]

Wifey's 2016 Leaf threw an EV System Warning Light yesterday and would not run but the lights and everything else working fine. The battery was at 98%. We plugged it in over night and it would run but the battery was still at 98%, but this time it threw the yellow Brake System Warning light.

Anyone know what the likely specific failure is? Battery has 11 bars and the mileage is 54,338. She has had in the past year or so occasional situations where she attempts to depress the brake in order to turn the car on and the brake gives a lot of resistance requiring her to press multiple times to engage it, and once it's engaged it works fine. She also has had a few occurrences (which we have chalked up to user error/impatience) in which attempting to put the car into reverse, it then goes into forward instead. Could this be related to the brakes system failure indicator?

 

[cwerdna]

Can you measure the voltage of the 12 volt battery?

 

[Wavebender]

Can you measure the voltage of the 12 volt battery?

I didn’t think of that but you may be on the right track. We took it to the Nissan dealer today and they said the 12v was weak and could have caused all our problems. Will advise as soon as it is confirmed.

 

[Wavebender]

The dealership replaced the 12v and everything checks out fine now. They ordered some parts from a recall involving a mounting component or something for the main battery array, so we won’t get the car back until Friday. I will report on the final verdict.

It does seem odd that a low voltage 12v battery should brick the Leafs brake system. Couldn’t shift out of park either, so it was basically stranded in our garage. I don’t know how the tow service would have gotten it onto the flatbed if we didn’t manage to get it rolling after over a dozen attempts.

 

[cwerdna]

It does seem odd that a low voltage 12v battery should brick the Leafs brake system. Couldn’t shift out of park either, so it was basically stranded in our garage.

If you couldn't get that car into READY mode (green car with arrows), you won't be able to shift to drive and that's the result of a dead or too low 12 volt. Jump starting it would be the workaround, or just replacing the 12 volt in your garage. I've done that before.

This is just like an ICEV with a dead 12 volt except that on Leaf, since there's no starter motor, you don't get the slow cranking or starter unable to turn the engine symptoms.

http://mynissanleaf.com/viewtopic.php?p=562002#p562002 is one thread I quickly found that seems to describe symptoms in the OP.

 

[Stanton]

...the 12v was weak and could have caused all our problems...

If I had a $1 for every time I've read that on this forum!

 

[Wavebender]

It’s been a few days since we got the car back and all is well with wifey’s Leaf. Excellent service at Bronco Motors here in Nampa ID. Thank you all for your helpful suggestions!

Drive on.