TCU Issue, please help.

My Nissan Leaf Forum

Help Support My Nissan Leaf Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

metzroth

Member
Joined
Sep 14, 2011
Messages
7
I am having a TCU issue that is causing the leaf to throw the yellow EV light on. Here's the DTC codes...

P312A 00C0 EV/HEV Comm Error EVC-208
P3131 00C0 EV/HEV System Shutoff Timeout
P31C2 00C0 EV/HEV TCU EVC-273
With a current code of....
U1000 000B TCU CAN Comm Circuit

My understanding of all this is that either the TCU has lost it's "activation" or is stuck on. Please confirm that understanding as well as offer any suggestions... like go to this area of the car and unplug the ^&*% TCU module :). My leaf has 106,000 miles on it and I don't want to go pay Nissan $149 just to unplug the TCU, re-activate it, or tell me I can pay them $350+$149 to fix it.
 
2 questions:
1) did you upgrade to the 3G TCU?
2) have you read the (very long) upgrade thread...which contains just about everything you want to know about the TCU?
 
2G upgraded to 3G in April 2016. Reading the threads, the first thing I’m going to try is unplugging the grey wire harness from it and see if the yellow warning light will disappear. While I’m under the glove box, I’ll change the cabin air filter as well since I’m already there :)
 
Just pull the fuse for the stereo/audio system under the hood to get the TCU unstuck. To mitigate the issue that seems to cause the P3131 DTC and the yellow ! car, see below.

http://www.mynissanleaf.com/viewtopic.php?p=515624#p515624
http://www.mynissanleaf.com/viewtopic.php?p=516453#p516453

Supposedly NTB18-045 addresses these probs. See http://www.mynissanleaf.com/viewtopic.php?p=531975#p531975. Unfortunately, I haven't seen the PDF of the TSB myself nor do I know if it's really effective yet. Will probably get it done in the near future.
 
Or follow the instructions here to disconnect the TCU entirely:

http://www.mynissanleaf.com/viewtopic.php?f=27&t=25949&p=528909#p528909

Note: this is for the 2G model but the 3g should be about the same.
 
IDK why, but I've been having more issues lately. About once a week now, where before it was only about once a month. I really wish there were an easy and permanent fix to this. I'm about to go and find the actual +12v supply to the TCU harness and install a toggle switch. Sometimes pulling the fuse doesn't solve it, and I'm tired of pulling the battery terminal, resetting the clock, and everything else.

Another thought was to just go and find a extremely low-power timer circuit that will automatically kill the power to the TCU once every few days for about 2 min.
 
LeftieBiker said:
I'm about to go and find the actual +12v supply to the TCU harness and install a toggle switch.

That was my suggestion, last year. I'd just turn the damned thing on when needed, leaving it off otherwise.

I’d always forget. But I was also thinking, maybe something more clever. Maybe have a relay staged off of accessory, so that when you shut off the car, it would momentarily power-cycle the TCU. You could do this with a simple relay, and 12v Super capacitor. The capacitor would draw current off of the relay when accessory is lost, momentarily keeping the relay triggered to break the circuit. Then once he capacitor is charged, the relay would then close the circuit.

This way, you’d always have a fresh system when you leave the car.
 
Supersleeper said:
IDK why, but I've been having more issues lately. About once a week now, where before it was only about once a month. I really wish there were an easy and permanent fix to this. I'm about to go and find the actual +12v supply to the TCU harness and install a toggle switch. Sometimes pulling the fuse doesn't solve it, and I'm tired of pulling the battery terminal, resetting the clock, and everything else.

Another thought was to just go and find a extremely low-power timer circuit that will automatically kill the power to the TCU once every few days for about 2 min.

What is the state of your12v battery? The 3g TCU is more sensitive to the voltage level than the 2g unit was. Since I replace the original 12v (over 4 years old) with a AGM style battery, the number of times the TCU had to be reset dropped considerably. Now, I only need to do a fuse pull (about 60 seconds) once every two to three months.
 
cwerdna said:
Just pull the fuse for the stereo/audio system under the hood to get the TCU unstuck. To mitigate the issue that seems to cause the P3131 DTC and the yellow ! car, see below.

http://www.mynissanleaf.com/viewtopic.php?p=515624#p515624
http://www.mynissanleaf.com/viewtopic.php?p=516453#p516453

Supposedly NTB18-045 addresses these probs. See http://www.mynissanleaf.com/viewtopic.php?p=531975#p531975. Unfortunately, I haven't seen the PDF of the TSB myself nor do I know if it's really effective yet. Will probably get it done in the near future.
I still haven't seen a copy of the DTC as NissanHelp.com still doesn't have it. A Google search did turn up https://www-odi.nhtsa.dot.gov/owners/SearchResults.action?searchType=PROD&prodType=V&targetCategory=A&activeTab=3&searchCriteria.model_yr=2015&searchCriteria.make=NISSAN&searchCriteria.model=LEAF&searchCriteria.prod_ids=1977440 which does have this text
2011-2015 LEAF; 12 VOLT BATTERY LOSES CHARGE AND/OR TELEMATICS SERVICES DO NOT WORK This bulletin applies only to vehicles equipped with a 3G Telematics control unit. IF YOU CONFIRM The 12 V battery continuously loses its charge and/or Remote Telematics services do not work. NOTE: DTCs P3131 (SYSTEM SHUTOFF ERROR) and/or P31C2 (TCU) may be found stored. ACTION 1. Refer to page 2, step 2 in the SERVICE PROCEDURE to confirm this bulletin applies to the vehicle being worked on. 2. If this bulletin applies, reprogram the Telematics control unit (TCU).
Yay! P3131 was exactly what I'd see accompanying the yellow ! car light when I had saved charging locations and auto-saving of them.

I'm having the car taken in for the annual battery check and will have them apply NTB18-045. Maybe I should go turn the auto-saving of charging locations tonight.
 
cwerdna said:
cwerdna said:
Just pull the fuse for the stereo/audio system under the hood to get the TCU unstuck. To mitigate the issue that seems to cause the P3131 DTC and the yellow ! car, see below.

http://www.mynissanleaf.com/viewtopic.php?p=515624#p515624
http://www.mynissanleaf.com/viewtopic.php?p=516453#p516453

Supposedly NTB18-045 addresses these probs. See http://www.mynissanleaf.com/viewtopic.php?p=531975#p531975. Unfortunately, I haven't seen the PDF of the TSB myself nor do I know if it's really effective yet. Will probably get it done in the near future.
I still haven't seen a copy of the DTC as NissanHelp.com still doesn't have it. A Google search did turn up https://www-odi.nhtsa.dot.gov/owners/SearchResults.action?searchType=PROD&prodType=V&targetCategory=A&activeTab=3&searchCriteria.model_yr=2015&searchCriteria.make=NISSAN&searchCriteria.model=LEAF&searchCriteria.prod_ids=1977440 which does have this text
2011-2015 LEAF; 12 VOLT BATTERY LOSES CHARGE AND/OR TELEMATICS SERVICES DO NOT WORK This bulletin applies only to vehicles equipped with a 3G Telematics control unit. IF YOU CONFIRM The 12 V battery continuously loses its charge and/or Remote Telematics services do not work. NOTE: DTCs P3131 (SYSTEM SHUTOFF ERROR) and/or P31C2 (TCU) may be found stored. ACTION 1. Refer to page 2, step 2 in the SERVICE PROCEDURE to confirm this bulletin applies to the vehicle being worked on. 2. If this bulletin applies, reprogram the Telematics control unit (TCU).
Yay! P3131 was exactly what I'd see accompanying the yellow ! car light when I had saved charging locations and auto-saving of them.

I'm having the car taken in for the annual battery check and will have them apply NTB18-045. Maybe I should go turn the auto-saving of charging locations tonight.

Hopefully, that really does fix the battery current draw (failure to power-down) problem and doesn't cause another problem.
 
^^^
Unfortunately, it has caused me a new problem. :( The TCU now is effectively non-functional. :( I probably don't have time to take care of it until Friday or another week. I'm busy w/other things + work.

Unfortunately, a post from the famed Leaf tech in the PNW awhile ago said "it is set as a TSB so would be out of warranty in some circumstances." My dealer had to charge me $85 for 1/2 hour of tech time. The SA also checked w/his manager about this. He suggested I take it up with Nissan corporate, to try to get my $ back. I told him it seemed pretty unfair given that I paid to have the TCU upgraded before June 2017 and there was fix until more than a year after I had that done.

Unfortunately, now it will not update stations at all. I receive "The connection to the center failed" 100% of the time. Refreshing status in the Nissan Connect app doesn't cause any update. I pulled the stereo fuse for several minutes and it didn't help.

I didn't have time to test nor troubleshoot at the dealer since I had to return to work, AT&T reception is unknown at the dealer, and I didn't have a fuse puller with me to see if that'd help. I couldn't look into it until I got home.

When the nav system shows the grey car at the top part of the screen, it always has the diagonal line thru it (like a NO sign). IIRC, it does take a bit of time after powering up for the TCU to become ready... but I already have waited a few minutes, each time, to no avail.

I tried a reset all Carwings settings on the nav system but that also didn't help. Dealer did give me a printout showing my VIN, system (TELEMATICS), saved date (this morning), etc., part number after programming being 283B0-3NF2B. Before was 283B0-3NF2A. I can see the 3NF2B in Leaf Spy Pro's service screen, for the TCU ECU revision.

SA seemed unfamiliar with the TSB until I told him the #. He printed out the 1st page and showed me (had the same verbiage as I quoted earlier). He said not a lot of people have come for them (my guess is probably because they didn't know about it) and that people that those leasing (presumably most Leaf drivers) don't care.

During our 1st conversation, he said that if the TCU was bad, they could replace it under warranty and there'd be no charge. But this wasn't a case (yet) of a bad TCU, but rather an update. I explained to him I was getting the TCU becoming unresponsive sometimes, requiring a fuse pull and the DTC P3131 until I deleted all my saved charging locations and turning off auto-saving of charging locations.

As an aside, he asked me how many capacity bars I was down (I was also paying for the dumb $40 annual battery check report, just to be on the battery defects warranty safe side). I told him 1. He was surprised. He said he'd seen much worse, esp. w/some drivers that QC only. I didn't press him on what he meant by that.

I got a call a few hours after I dropped off the car saying the TCU was rejecting the update for some reason and that they'd try again. The call later in the day was that car was done.
 
Thanks for the update @cwerdna
If I'm reading this correctly, we should not do the TCU software/firmware update at this time. Since I haven't had any TCU issues for months (I turned off the "saved charger locations" or whatever it was), I'm thinking I should never do it...unless I don't want to talk to my Leaf anymore... ;)
 
^^^
For now, yes. The PNW Leaf tech believes my dealer's tech forgot to turn the TCU back on afterward. (My dealer's Leaf tech was apparently not working that day so they found someone else. :( All the work they needed to do would've been thru Consult III Plus and doesn't require any sort of EV hardware/mechanical knowledge.)

Will be bringing the car in again tomorrow.

update: Brought it in, told them what the above Leaf tech suggested. That was it! They turned the TCU back on and it's working now. We'll see if it fixes the issues that I'd been experiencing before. Will re-adding back saved charging locations and turning back on those reminders.
 
cwerdna said:
^^^
All the work they needed to do would've been thru Consult III Plus and doesn't require any sort of EV hardware/mechanical knowledge.)

For those DIY types;

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=Consult+III+Plus&_sacat=0

May require a logon to Nissan, though.
 
I know this is a bit of a zombie thread, the CAN errors showed up for me on the 2G TCU when the white cable was unplugged. I would check the connections in the white cable and verify it's fully inserted.

Grey connection being disconnected throws U1266 and U1A05. Blue cable throws a code about the TCU antenna being unplugged.

See here:
http://www.mynissanleaf.com/viewtopic.php?t=25949
 
My TCU issue was that the Nissan app would not connect, that is would not get the status from the car. I believe that was due to the TCU getting stuck when the battery (lead acid) voltage dropped a bit.
I did the NTB18-045 update last wednesday and my app is working fine, so far so good.

John
 
I got 18-045 last week and it seems to stop problem. I was waking up to see empty 12v battery every 3-4 days when LeafSpy showed battery ok (12.88 v) 11 PM night before. Along with it were yellow exclamation alert and TCU not comnnecting. No instances since.

Though I told him it was the TCU, he had to do 12v battery check (ok, same as Autozone tech found) and overall amp leak check, no leaks. I then used NissanConnect to show impact of TCU when operated. He was surprised to see a 20 amp drain ( for a fraction of a second). He agreed if TCU stayed open, even a great 12v would not last long.

18-045 is a software only change. Dealer treated it as warranty item, I.e., no charge.
 
Back
Top