2012 model cabin heater

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Well-known member
Feb 28, 2014
Sydney Australia
Greetings all. My 6 month old 2012 model Leaf cabin heater failed in May. Yes Vanessa it takes that long for new tech to filter down here to Australia. I was going to wait for the 2013 model with the reverse cycle AC to arrive but decided I might be in a retirement home by then & decided to go with the kettle.

Anyway, I checked the water temperature sensor resistance (with an ohm meter) & the heater fluid circulation pump (liquid moving in the reservoir) & both were OK so decided it must be the ceramic heater. I was confident of a fix at my 10k service. It didn't happen!

The dealership have been swapping parts seriously now this last month. They have replaced the heater, the pump & the centre console, still no joy. I'm worried this device swapping methodology could drag on forever & was hoping for a more diagnostic approach.

I've read all the service manuals I can find for the 2012 model but can't actually find a circuit diagram for the cabin heater wiring. Does anybody know where the switch that routes traction pack power to the PTC heater is physically located? Surely checking that should help narrow down where the problem lies?

Any feedback not involving lawyers gratefully accepted.
I believe that the DC/DC junction box (combination of dc/dc converter and HV junction box) is what gives the heater the HVDC "juice". However, like you I have the service manuals in front of me but I can't seem to find anything on this. I'll keep looking though! :)
Thnx chief. I figure the power switch that runs the heater should be where the supply, load & control cables all meet. A multimeter should at least ferret out which is the culprit.
Aren't there any trouble codes in any systems? The dealer should have performed a global scan of all the modules. (As techs, we do all modules because sometimes the source of a problem in one system is with a different system.)

Hopefully you have seat and steering wheel heaters to fill the gap!!!!
Finally got it back after 6 weeks, a junction box problem. Would like to know more but dealerships sort of put a wall between car owners & the mechanics.
Looking at the 2012 service manual EVC circuit diagram on page 29, the only component
in the Junction box for the heater is a 30 amp fuse for the high voltage positive. That would
take a lot of watts to blow. I wonder if a failing heater unit can do that, or maybe something
in the junction box that can cause a short.
My copy of the manual is divided into 5 sections;
Heater & AC
Heater & AC control
none of 'em have a circuit diagram on P29, am I missing a book?
Kris1 said:
none of 'em have a circuit diagram on P29, am I missing a book?
You seem to have something different than what I have. What I have
says Edition September 2011 (which is what existed in September 2012, and was
labeled "2012 LEAF" at the bottom),
Publication SM2E-1ZE0U0. The document I was looking at was a pdf from
Section C ELECTRIC POWER TRAIN, subsection EVC, and the pdf was
Nissan has a web site that for a small fee allows one to view the Service manual for a single day.
Many have saved the documents from this site, which I suppose copyright fair use might
allow in some cases.