T/M System Malfunction

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iamchemist

Well-known member
Joined
Mar 18, 2011
Messages
57
Location
Wilmington, NC
I went to start my 2015 LEAF SL a few days ago and got the error message "T/M System Malfunction". The car would not start or allow me to put in into gear.

I feared that there was something major wrong with the transmission.

Thanks to this forum I leaned that this message is often seen, when the 12 V battery voltage is low, which usually happens when the battery is failing.

Sure enough, my battery (only 3 years old and lives in a mild climate) was only charged to 8.3 volts, which is apparently low enough to totally confuse the computer systems in the car and produce a bogus error message.. Removing the battery, charging it up to 12 volts, and replacing it allowed the car to start normally. Replacing the battery with a new one appears to have completely fixed the problem.

Note that this all happened, while I waited for Nissan Service to call me back. They finally did call back about 8 hours after I had called and requested a call back. The initial Nissan Service person that I talked to suggested that I might be able to jump start the car. This is typical of the things I hear from Nissan Service about my LEAF.
 
iamchemist said:
Sure enough, my battery (only 3 years old and lives in a mild climate) was only charged to 8.3 volts, which is apparently low enough to totally confuse the computer systems in the car and produce a bogus error message..
Yeah; bummer. See, most microcomputer systems need something like 3.3V to operate, and while it may someday be possible to derive 3.3V from a raw supply that's fallen from 12V to 8V, it's not reasonable to expect Nissan to pull a miracle like that off just now. And besides; those computers probably need a dozen milliamperes or more to run; not the sort of punch that you could reasonably expect from a battery that's only intended to crank a starter motor. Well, maybe you can when it's in tip-top condition, but not one that's been kept on a starvation diet for a few years. Some might wonder whether, on its way down from 12V to 8V, the system computer could find twenty microseconds to record a trouble code signifying, "hey! my misapplied battery's toast!". Dreamers.
 
Levenkay said:
Yeah; bummer. See, most microcomputer systems need something like 3.3V to operate, and while it may someday be possible to derive 3.3V from a raw supply that's fallen from 12V to 8V, it's not reasonable to expect Nissan to pull a miracle like that off just now. And besides; those computers probably need a dozen milliamperes or more to run; not the sort of punch that you could reasonably expect from a battery that's only intended to crank a starter motor. Well, maybe you can when it's in tip-top condition, but not one that's been kept on a starvation diet for a few years. Some might wonder whether, on its way down from 12V to 8V, the system computer could find twenty microseconds to record a trouble code signifying, "hey! my misapplied battery's toast!". Dreamers.

That post is sarcastic gold. Thanks for making my day.

Add to it: It's also a shame that there's no way to remove the 12v battery entirely. If only there were a large battery of sufficient power, we could avoid the lead acid one entirely...
 
Thank you folks - this appears to be our issue: Complete electric dashboard meltdown/freakout!
We initially saw this when rescuing our daughter with a flat tire. We used the 'nissan' fix-a-flat air compressor to inflate a flat tire due to a slow air leak. Apparently - this was enough to dip the 12v battery below the threshold voltage required to properly boot the system. Unclear what was actually wrong - I decided to attempt a brief top-off charge from a nearby 110 outlet for three minutes. Retried - and suddenly all was good. Several days later this all happened yet again without any 'discharge' provocation as we had before - nonetheless; a brief connection to our charging system seemed to get this to start OK. We've never replaced or touched our 2016 SL 12v. battery before - so we'll replace that ASAP. This forum ROCKs!
 
Always use Ready Mode, NOT Accessory Mode, to run high drain things like air compressors from the car. Accessory mode shouldn't even be an option in most EVs.
 
This was exactly the problen with my 2015 leaf today. Couldnt even get it out of the garage. Luckily I found this before calling auto service.

Also luckily, i didnt sell off my 12V battery charger when I went all electric. I figured i would never need that thing again, but it sure saved me today.

Im not sure how long i can expect a recharge to last before i get this again. My battery sticker is 1/17, so my 80 month old battery seems ready to give it up about on time relative to the 84 month life listed on the side. I replaced it with an interstate battery from Costco, figuring I didnt want to really test out how long it will take before the problem happens again.

Thanks to everyone for posting a solution that had nothing to do with the message on the screen. You saved me a lot of time and aggravation today.
 
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